A CAT tourniquet, short for Combat Application Tourniquet, is a lightweight device designed to completely stop arterial blood flow from a severely bleeding limb. Originally developed through research at the U.S. Army Medical Research and Materiel Command, it became standard issue for military personnel and has since become one of the most widely carried tourniquets by civilians, law enforcement, and first responders.
How a CAT Tourniquet Works
The CAT uses a wide nylon strap that wraps around a limb, combined with a plastic rod called a windlass. You tighten the strap around the injured arm or leg, then twist the windlass rod to increase pressure until blood flow to the wound stops completely. Once tight enough, the rod locks into a clip on the device, and a hook-and-loop strap secures everything in place so it won’t loosen.
The device is small enough to carry in a cargo pocket or clip to a belt, and it’s designed for one-handed application, meaning you can apply it to your own arm or leg if needed. This self-application capability was a key design requirement for military use, where a wounded soldier might be alone or under fire.
Testing has shown the CAT achieves arterial occlusion (completely cutting off blood flow) in 100% of limbs tested in controlled settings, including on children as young as two years old. The current production version is the Generation 7, manufactured by North American Rescue under the brand name CAT Resources (formerly Composite Resources).
Safe Time Limits
A tourniquet left on too long can cause serious damage to the tissue below it, since you’re cutting off all blood supply. The widely accepted safe window is under two hours. Tourniquets used for less than two hours have proven safe even in cases where they turned out to be unnecessary. Beyond two hours, the risk of significant tissue injury rises sharply.
If the tourniquet has been on for less than six hours, medical providers will typically attempt to convert it to a pressure bandage or reposition it closer to the wound. Tourniquets in place longer than six hours are generally left alone because removing them at that point carries a high risk of requiring amputation. This is why writing the time of application on the device (there’s a white strip for this) matters so much.
Common Application Mistakes
The CAT is simple in concept but surprisingly easy to use incorrectly, even among trained personnel. Military training identifies three critical failures: placing the tourniquet too close to the wound, not twisting the windlass enough to stop bleeding, and not properly securing the device afterward. Any one of these can be fatal.
In a study of medical trainees, about 35% placed the tourniquet too low on the thigh. The correct placement is at least two inches above the wound, and in an emergency where you can’t clearly see the injury, the guidance is to go “high and tight,” placing it as high on the limb as possible. Nearly 30% of trainees in the study failed to apply the tourniquet first, instead reaching for other supplies, which wastes critical seconds during severe bleeding.
The windlass is where most people fall short. Research has found that roughly 6.5 half-rotations of the windlass rod are needed to stop blood flow in all cases, while 3.5 half-rotations only succeed about 67% of the time. In the trainee study, just over half achieved 3.5 half-rotations, and not a single participant reached the 6.5 mark. The takeaway: most people don’t twist the windlass nearly enough. It should hurt. If the person isn’t in significant discomfort, it probably isn’t tight enough.
Another overlooked step is removing slack from the strap before you start twisting the windlass. If the band is loose around the limb, you’ll waste several full turns of the windlass just taking up that slack, and may run out of effective rotation before blood flow actually stops.
How to Spot a Counterfeit
Counterfeit CAT tourniquets are widespread online, and they can fail catastrophically when you need them most. Fake windlass rods snap under pressure, fake buckles crack, and poorly bonded seams tear apart. If you’re buying a CAT for your first aid kit, knowing the difference could save a life.
Price is the fastest indicator. A genuine CAT costs $30 or more. If you’re seeing them for under $25, it’s almost certainly a counterfeit.
On a real CAT, the seams are sonically welded, creating a smooth, solid bond. Counterfeits often use thermal bonding, stitching, or glue that separates under tension. The buckle on a genuine device is slightly curved, made from rigid plastic that resists bending. Fake buckles feel flimsy and bend with finger pressure.
The Generation 7 has several specific markings worth checking:
- Buckle: Raised black “C-A-T” initials on the routing buckle and both ends of the windlass rod, readable from either direction.
- Windlass rod: Sturdy with raised ribbing for grip. Fakes often have smooth, brittle rods. Older genuine versions (Gen 3 and Gen 6) have groove cuts instead of raised ribbing.
- Windlass clip: Thick and rigid. The Gen 7 has the thickest clip of any version. If you can bend the clip easily with your fingers, it’s fake.
- Strap tail: Red on Gen 6 and Gen 7 models (black on Gen 3). The manufacture date is stamped on the tail end, along with CAT branding, the National Stock Number, and lot information.
- Strap length: Genuine CATs measure approximately 35 inches. Counterfeits are often about 5 inches shorter.
- Stabilization plate: The back of the plate displays “C-A-T,” the manufacturer’s website, and other details in 5mm mold markings.
Buy only from North American Rescue directly or from authorized distributors. Third-party marketplace sellers, even on major platforms, are a common source of counterfeits.
Why Civilians Carry Them
The CAT was designed for combat, but severe limb bleeding happens in everyday life: car accidents, power tool injuries, farm equipment incidents, mass casualty events. Bleeding from a major artery can cause death in minutes, well before an ambulance arrives. A tourniquet in a glove box or range bag bridges that gap.
The device works on arms and legs of all sizes, from small children to large adults. Its one limitation is that it cannot be used on the torso, neck, or areas where you can’t wrap a strap around a single limb. For those injuries, wound packing with hemostatic gauze is the standard approach.