Strong Enough
To Protect
Strong Enough
To Protect
Designed to be used every day.
The Facts
What is The Defender Harness Safety System?
This is a crash-tested dog restraint system designed to manage collision forces using multiple attachment points.
It consists of:
- A Defender Harness
- An Upper Tether
- A Lower Tether
All components are designed to work together. The system is not intended to be used partially.
A system, not Another Harness
This isn’t a single connection.
It’s a system designed to manage force across multiple load paths.
Each component has a job — before impact and during it.
That’s intention.
Why a system (not a single tether)
In a crash, force is applied suddenly when the seatbelt locks.
Single-point restraints concentrate that force at one connection.
Our Multi-point systems distribute force across structure and time.
This system uses:
- One connection to manage position and pre-tension
- One connection to engage once the seatbelt locks
This reduces peak load on any single component.
Materials and Durability
The harness body is constructed from 1000D Cordura® nylon, a material commonly used in applications where abrasion resistance, tear strength, and long service life are required.
1000D Cordura® is chosen because:
- It resists abrasion from repeated contact with vehicle interiors, pavement, and terrain
- It maintains structural integrity under load and repeated flexing
- It performs consistently across temperature changes and moisture exposure
This is not a decorative fabric.
It is selected for long-term durability under real use, not short-term appearance.
The material is intended to withstand years of daily wear without compromising the structural function of the system.
How Force is Managed
In a collision:
- The lower tether is already loaded because it holds the dog in a stable sitting or lying position.
- The dog may move forward slightly as the seatbelt begins to take up load.
- The seatbelt locks.
- Load transfers through the upper tether into the system.
- The harness structure distributes force across the dog’s torso.
- The lower tether limits rotation and secondary motion, helping keep the dog stable as forces resolve.
The goal is not to stop motion instantly, it’s to control deceleration in a predictable way.
Hardware and Materials
- Purpose-built metal hardware, including Optimus Buckles, designed and manufactured in-house
- Multi-directional, load-rated stitching aligned with primary load paths
- Reinforced load paths built into the harness body to distribute force
- Components designed to fail last, not first, under extreme load
Existing off-the-shelf buckles presented a tradeoff:
hardware small enough for daily comfort lacked sufficient strength, while hardware strong enough for crash loads added unnecessary bulk and weight.
To resolve this, Optimus Buckles were designed and manufactured in-house, allowing strength, size, and comfort to be balanced intentionally rather than compromised.
No single clip, buckle, or strap is intended to carry the full crash load.
What “Crash-Tested” Means
This system has been dynamically crash-tested using sled test protocols derived from FMVSS / CMVSS 213, the standards used for child restraint testing.
Testing evaluates:
- Structural integrity of the system
- How load moves through the harness and tethers
- Hardware retention under dynamic load
- Whether deceleration is controlled rather than abrupt
A successful test demonstrates that the system remains intact, maintains occupant containment, and avoids catastrophic failure under standardized crash conditions.
The Crash Safe Defender Harness has successfully completed these tests in XS, S, M, and L sizes.
XL will be tested in our next scheduled test run.
Common Questions
Is it comfortable for daily use?
Yes. The system is designed to remain on the dog between drives, reducing setup friction.
Do I need to adjust it every trip?
No. Once fitted, daily use requires only clipping and unclipping.
Can I use it without both tethers?
No. The system relies on multiple attachment points to manage force.