Optimus Gear Defender Harness Review: A Versatile Crash-Tested Dog Harness Perfect for Car Travel and Everyday Use

Are you in search of a top-notch dog harness that not only ensures your furry friend’s safety during car travel but also doubles as a versatile everyday harness as well? Look no further! In our latest review, we’ve put the Optimus Gear (OG) Defender Harness to the test, and the results are impressive. Join us as we explore this innovative Canadian-made harness, designed to keep your pup safe and secure in the car whilst ready for any adventure!

Disclaimer: Optimus Gear generously gifted us with one of their Elite Harness Kits for testing and review, however, all thoughts and opinions expressed in this post are our own.

OG Defender Harness Crash-Tested Dog Harness Review - feat. Django the Cocker Spaniel wearing a size 'medium' OG Defender Harness, + a picture of the OG Defender Elite kit

Above left: Django (English Cocker Spaniel) wears a size Medium OG Defender Harness. Above right: Crash-tested dog harness kit contents with both small/medium and a medium double-legged tether (the same style used in the large and x-large sizes).

Who is Optimus Gear?

Optimus Gear is a premium Canadian pet brand specializing in dog vehicle safety products that combine versatility, crashworthiness, and engineering for a lifetime of use.

Launched in the spring of 2021 with a mission of promoting safe dog vehicle travel, Optimus Gear’s flagship product, the OG Defender Harness, represents a revolutionary all-in-one dog seat belt and harness system that not only ensures your pup’s safety during car journeys but also offers versatility for a wide range of other activities, too.

OG Defender Harness Unboxing and Kit Contents

Upon unboxing our kit, one of the standout features that immediately caught our attention was the custom hardware, which is both unique to Optimus Gear and distinctly different from any other dog gear hardware we’ve encountered before.

Crafted from aircraft-grade aluminum, Optimus Gear’s patented clips are engineered to exhibit exceptional strength and durability and have undergone rigorous testing in various conditions, proving their ability to withstand daily wear and tear while maintaining their integrity even in the event of a crash.

Notably, the x-large harness clips even boast an impressive, rated break strength of over 4000 lbs!

OG Defender Harness custom hardware

Above: Patented OG hardware feat. 1 of 2 back leash connection points (left), and the OG leash converter and small/medium vehicle tether (right).

Another noteworthy aspect is that the harness is offered as part of a kit, with three options available: standard, premium, and elite. We were fortunate to receive an elite kit, which includes the harness itself, vehicle tethers, an OG leash, an OG collar, an OG leash converter, a poo bag roll holder, and a convenient storage/washing bag.

Additionally, OG generously provided us with a medium two-leg lower tether (the same used in the large and X-large size kits), in addition to the typical single-leg medium tether, allowing for a thorough comparison and review.

The kit you select will ultimately determine the number of accessories you receive, although all kits include the harness, OG leash converter, and vehicle tethers as standard. Currently, the OG Defender Harness is available in four sizes (small, medium, large, x-large), and it comes in six different colors.

For small and medium harness kits, both a seatbelt and a carabiner tether are included. In the large and x-large harness kits, you’ll receive a carabiner tether (like the small and medium kits) as well as a stronger, more robust dual-clip tether designed to connect to the lower child seat anchor points in your car’s back seat (we tested both options).

Both premium and elite kits come with an OG leash included, utilizing the same OG patented hardware. However, the standard kit does not include a leash, making the OG leash converter a useful addition. This means you can fully utilize the harness’s many features even if you prefer to use your own non-OG leash.

OG Defender Harness Crash-Tested Dog Harness Review - feat. the OG Leash and OG leash connector

Above left: OG Leash connected to the OG Defender Harness, Above right: Non-OG leash connected to the OG Defender Harness using the OG Leash Converter (supplied in all harness kit configurations).

OG Defender Harness Vehicle Tether Installation and Fitting

The installation of the vehicle tethers proved to be straightforward, especially after watching OG’s informative installation video. However, if you’re using the vehicle tether provided in a large or x-large kit, it’s essential to be aware that certain types of dog car seat covers may obstruct access to the lower child seat anchor points required for installation.

If you’re not using a seat protector, or if you’re using one of OG’s own car seat covers, you shouldn’t encounter any issues accessing the lower anchor points.

It’s also worth noting that the OG Defender Harness vehicle restraint system employs two connection points in your car, as opposed to the single point utilized by many other dog car harness brands. This design provides comfort and crash-worthy protection for your furry friend, whether they’re sitting or lying down during car travel.

OG Defender Harness vehicles tethers installed in the back seat of a car

Above left: Large/x-large style vehicle tethers installed. Above right: Small/medium vehicle tethers installed.

Selecting the correct size and fitting the harness to our dog was a hassle-free process, thanks to OG’s well-defined website sizing chart and the multiple adjustment points on the harness itself. For those unsure about the best size for their dog, simply reach out to Optimus Gear support by email with your dog’s measurements and weight, and they will be more than happy to assist with a size recommendation and even customize the strap sizing if necessary.

What We Liked and Disliked About the Harness as a Vehicle Restraint

When it comes to using the harness as a vehicle restraint, our list of likes substantially outweighs any minor drawbacks we encountered during our testing. Here are some of the standout features we appreciated:


  • Durable Padded Chest Plate: The harness’s padded chest plate not only ensured a comfortable fit for our pup but also allowed for a full range of unimpeded movement. The outer fabric and heavy-duty stitching impressed us with their high-quality feel, without being overly thick or rigid.
  • Adjustability: The OG Defender Harness boasts four adjustment points—two around the neck and two around the chest—allowing us to achieve a nearly perfect fit for our dog.
  • Seat Belt Cover Plate (Small/Medium Lower Tether): This addition is particularly useful for the small and medium harness sizes. It helps prevent your pup from accidentally stepping on the seat belt button and releasing the clip while traveling—a scenario we’ve experienced several times with other brands!
  • Appropriate Tether Lengths: The vehicle tethers strike the right balance. They are short enough to keep your pup securely on the back seat in the event of a crash or sudden stop, yet long enough to allow them to sit or lie down comfortably while on the move.
  • Easy Tether Installation: Thanks to OG’s informative installation video, vehicle tethers are a breeze to install.
  • Successful Crash Testing: We were reassured to learn that the small, medium, and large size OG Defender Harnesses have undergone successful crash testing using dog mannequins at the MGA Research facility in Virginia, and are engineered to safely withstand crash forces of up to 50 km/h or 30 mph.
  • Harness Replacement Program in Case of a Crash: Optimus Gear’s commitment to safety extends to its harness replacement program in the event of a crash. We appreciate that they offer to replace compromised harnesses, ensuring that each dog gets the safest travel experience possible every time they’re in the car. You can find more details about their replacement program here.


While our experience with the OG Defender Harness as a vehicle restraint was largely positive, there were some aspects that we found less favorable, for example:

  • Incompatibility with Some Dog Car Seat Covers: The large/x-large tether clips may not be compatible with certain brands of dog car seat covers on your back seat as they may prevent access to the lower child seat anchor points required for the OG large/x-large vehicle tether. This limitation was the case for us. However, if you’re using an OG brand car seat cover or no cover at all, this issue doesn’t arise.
  • Leash Attachment While Traveling: The OG harness system utilizes BOTH back harness clips during car travel. If you wish to leave your leash attached for a quick exit once you’ve stopped, you are limited to the leash attachment point on the front of the harness. Alternatively, you would need to spend an extra second or two detaching one of the tether clips before attaching your leash to the back of the harness prior to exiting.
  • Lack of Center for Pet Safety (CPS) Certification: While OG conducted crash testing with dog mannequins at the MGA Research Facility in Virginia and successfully crash-tested their small, medium, and large harnesses, they are not currently CPS Certified.
  • X-Large Size Not Officially Crash-Tested Yet: The x-large OG Defender Harness is a relatively new addition to the range and has not yet undergone official crash testing. However, the hardware and design employ the same technology as all smaller sizes, and OG’s own static tests have demonstrated that the buckles can withstand forces of over 4000 lbs. When questioned about the crashworthiness of the x-large harness, OG advised that based on their calculations and results for the other sizes, they are confident that the harness will be able to withstand crash forces of a 140 lbs dog traveling at 50 km/h, with plans to officially crash-test the harness in their next round of testing.
  • Absence of X-Small Size: Currently, there is no X-small size available, although there are plans for the release of an X-small size in early 2024.
  • Premium Price: While we were fortunate enough to receive our kit in exchange for this review, it’s worth noting that these kits are not inexpensive and may not fit into everyone’s budget, especially those with multiple dogs.

What We Liked and Disliked About the Harness as an Everyday Harness

Beyond its use as a vehicle restraint, the OG Defender Harness continued to impress in everyday situations. Here’s what we found appealing and any concerns we encountered:


  •  Versatility: The OG Defender Harness proves to be highly versatile. With multiple leash attachment points (2 on the back and 1 on the front) and a wide range of optional accessories available, it seamlessly transitions from a dog car seat belt to an everyday harness in seconds and is suitable for activities like walking, running, towing, obedience training, and more.
  • Robust Materials and Hardware: As previously mentioned, OG’s patented hardware stands as a testament to its premium quality. Clipping and unclipping are effortless and can be done with a single hand. Additionally, the materials used are sturdy yet comfortable for your dog.
  • Ergonomic Design: The design of the chest plate does not hinder freedom of movement, making it ideal for various activities like walking, jogging, and towing.
  • OG Leash Converter: The OG leash converter supplied in all OG harness kits makes it easy to use the harness with non-OG leashes if desired.
  • OG Leash (In Premium and Elite Kits): The OG leash provided in both the premium and elite kits features a convenient poop bag hook and a comfortable padded handle. Its length is suitable for everyday activities like walks and runs, and it includes a swivel connector to prevent twists and tangles.
  • Generous Size Range with Custom Sizing Available: Currently, the OG Defender Harness is available in four sizes, with a fifth size set to become available in early 2024. For those unsure about the best size for them, custom strap sizing and sizing recommendations are also offered.
  • 1-Year Manufacturer’s Warranty (+ Harness Replacement Program in the Event of a Crash): OG stands behind its product with a 1-year manufacturer’s warranty. Additionally, their harness replacement program, in the event of a crash, provides peace of mind, ensuring your dog’s safety is a top priority.


While the dislikes we encountered were relatively minor and often dependent on personal preference, here are the aspects that stood out:

  • Bulky: Some dogs or their owners might perceive the OG Defender Harness as slightly bulkier compared to other everyday harnesses due to the presence of both a chest plate and a back plate. It’s essential to note that this perception varies from one individual to another and is primarily a matter of personal preference.
  • Exiting the Car: As previously mentioned, when using the harness as a car restraint, both rear leash attachments are in use, preventing you from leaving your leash attached to the harness while traveling (unless you utilize the front attachment point). While it only takes a few seconds to unclip the vehicle tether and re-attach your leash, if you have an excitable dog, this process may take longer.
  • Premium Price: Once more, it’s worth mentioning that while highly versatile, this system comes with a premium price tag and may not fit into everyone’s budget.

Do We Recommend the OG Defender Harness?

After testing multiple dog car seat belt systems in the past, including other crash-tested dog harness designs, the OG Defender Harness stands out to us as an exceptional all-in-one vehicle restraint and everyday harness. It’s difficult to find a harness that offers such versatility, prioritizes safety, and is built to endure. As such, we wholeheartedly recommend the OG Defender Harness to anyone seeking a multi-functional harness that places safety at the forefront and is designed to withstand the test of time!

Where to Buy the OG Defender Harness

The OG Defender Harness range, proudly designed and manufactured in Canada, is currently available through the Optimus Gear website. It comes in four sizes (soon to be five), and six colors, and is available in three harness kit configurations to suit your needs.

For those located outside of Canada and the USA, international shipping is also available, making it accessible to dog owners worldwide.

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