A windlass can only tighten what the strap has already taken up. Pull the slack out first — the wedge under the SOF® windlass is there to show you when you have.
At a glance
12 things to know about the SOF® Tourniquet
What changed in the fifth generation, how it works, and what the independent studies of the SOF design found.
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01
It is the fifth generation of the SOF® Tourniquet
TacMed's FDA device records list this SOF® Tourniquet as version 5 and describe it as the newest evolution of the design; TacMed's patent schedule names it the SOF Tourniquet Gen 5.3,6 TacMed still sells the previous generation separately as the SOF® Tourniquet Gen 4 (SOFTT-W).5
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02
A true 1.5 in. strap
The Performance Compression Band is reinforced, low-stretch polyester webbing at a true 1.5 in. width, built to glide through the buckle in one-handed and two-handed applications.3 The original SOF Tactical Tourniquet used a 1 in. strap and is no longer on the evidence-based list; the 1.5 in. width is the "W" — Wide — in SOFTT-W.7,8
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03
A wedge that shows when the slack is gone
A contrasting slack indicator wedge is stitched into the band below the windlass. When it shows, the excess slack is out of the strap, and fewer windlass turns are needed to stop the bleeding.3 Slack matters: in a manikin study of an earlier SOFTT-W, failed applications carried 10.5 mm of slack against 3.2 mm in successful ones.13
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04
Machined aluminum windlass, two-stage lock
The 5.5 in. windlass is machined from a single aircraft-grade aluminum bar, anodized, with conical ends and a textured grip.3 The TRAC (Tourniquet Retention Assistance Clip™) holds the windlass for a moment while you get a hand free; the Tri-Ring Lock™ is the lock. TacMed's instructions mark the TRAC as optional and the Tri-Ring Lock as the step that secures the tourniquet.4
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05
The buckle opens for a trapped limb
Normally the SOF® Tourniquet slides over a hand or foot as a closed loop. If the limb is pinned, lift the buckle, twist it to disconnect, pass the band around the limb, reconnect and carry on — no rethreading.4
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06
One method for the arm and the leg
TacMed's instructions use the same six steps on either limb: slide it on above the injury, pull the tail tight, twist until the bleeding stops, brace the windlass in the clip if you need to, lock it in the triangle, and note the time.4
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07
Lighter than the Gen 4
The fifth generation weighs 3.7 oz (105 g); the Gen 4 SOFTT-W weighs 4.2 oz. It folds to 5.5 × 2 × 1.5 in. and opens to 40 in.3,5
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08
Stage it ready to slide on
TacMed's storage instruction is to keep the buckle connected with enough slack to slip the loop over your limb.4 Take it out of the factory packaging, keep it pouched or covered and out of the weather — on body armor especially — and carry it where either hand can reach it.
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09
It has its own NSN
The black SOF® Tourniquet, part 84-0009, is stocked under NSN 6515-01-696-4522. The Gen 4 SOFTT-W carries a different NSN, 6515-01-587-9943.3,5,7
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10
Designed by a Special Forces medic
TacMed states the patented SOF® Tourniquet was designed by a Special Forces medic on deployment in Afghanistan in 2003.6 The original SOF Tactical Tourniquet was one of three, of seven tested, that stopped distal arterial flow in every volunteer in the U.S. Army Institute of Surgical Research's 2005 self-application study.15
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11
The evidence on the SOF design is mixed — read all of it
Earlier SOFTT-W generations trailed the C-A-T in volunteer and manikin testing: 58% versus 6% failure on the arm, and 35% versus 68% hemorrhage control on a manikin leg.12,13 In a 2023 live-thigh study that included this fifth generation, 1 of 64 Gen 5 applications was not correctly secured, against 47 for the C-A-T Gen 7 and 31 for the TMT.10 The design changed between those studies; the evidence table below shows each one.
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12
Single use — and Trainer Blue is for practice
TacMed labels the SOF® Tourniquet for single use.4 One that has gone on a casualty is replaced. Trainer Blue (84-0011) is the training device: practice with it, and never stage it for duty use.3
How to apply the SOF® Tourniquet
TacMed's application steps, with placement and follow-up from the TCCC Guidelines.
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1Decide where it goes. Under threat, or when you cannot see where the blood is coming from: hasty — high and tight, as far up the limb as it goes, over clothing. When the scene allows and you can identify the source: deliberate — on bare skin, 2–3 in. above the wound; if that point lands on a joint, move above the joint. Never across or directly over a joint.1
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2Slide it on. Open the loop, slide it over the hand or foot and up the limb above the injury. If the limb is trapped, unclip the buckle, pass the band around and reconnect it.4
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3Pull the tail tight. Pull hard until the strap is snug and the slack indicator wedge shows the slack is out.3,4
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4Twist the windlass. Turn it until the bleeding stops and the pulse below the tourniquet is gone. It hurts — that is expected.1,4
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5Lock it. Brace the windlass in the TRAC if you need a free hand, then lock it in the Tri-Ring Lock™. The TRAC alone does not secure it.4
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6Still bleeding? Add a second. Tighten further; if one tourniquet does not stop the bleeding, apply a second one side-by-side with the first.1
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7Write the time. Mark the time on the tag and on the casualty card.1,4
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8Reassess when you can. Expose the wound. To convert a hasty tourniquet, put a second one on bare skin 2–3 in. above the wound, tighten it, then slowly release the first. If you still cannot identify the source, it stays high and tight.1,18
Where it fits
- Life-threatening bleeding from an arm or a leg
- A traumatic amputation, even one that is barely bleeding — adrenaline constricts the arteries, and when it wears off they open and the bleeding starts
- Self-application with one hand3
- A trapped limb — the buckle unclips to go around it4
- Junctional wounds — the groin, armpit and neck — where a limb tourniquet cannot be placed; pack them with a hemostatic dressing and hold pressure1
- Placement across or directly over a joint
- Bleeding that firm direct pressure or a pressure dressing controls
- Practice — use Trainer Blue, and never stage Trainer Blue for duty use
The evidence
Every study cited above, which SOF generation it tested, and how strong the evidence is.
| Study | Evidence type | What was studied | What it found |
|---|---|---|---|
| Wall et al., J Spec Oper Med 202310,11 | Human · live-thigh volunteers | 64 appliers each applied 8 tourniquets, including the SOF Gen 5, SOFTT-W Gen 3, C-A-T Gen 7 and TMT, to live thighs with a Doppler pulse | Not correctly secured: 1 SOF Gen 5 application vs 47 C-A-T Gen 7 and 31 TMT. From a tight strap, occluded and secured applications took 9.19 s from first touch of the windlass to "done" with the Gen 5 vs 14.47 s with the C-A-T Gen 7 |
| Treager et al., J Trauma Acute Care Surg 202112 | Human · randomized crossover | C-A-T Gen 7 vs TMT vs SOFTT-W (earlier generation), arm and leg, volunteers, Doppler endpoint | Arm failure 5.56% C-A-T, 19.44% TMT, 58.33% SOFTT-W; leg 27.78%, 44.44%, 61.11%; after a crawl and drag, no significant difference |
| Katsnelson et al., Mil Med 202013 | Manikin · randomized | C-A-T Gen 7 vs SAM XT vs SOFTT-W (earlier generation), HapMed leg trainer, 60 military medicine cadets | Hemorrhage control 67.7% C-A-T, 73.3% SAM XT, 35% SOFTT-W; slack 9 mm with SOFTT-W vs about 5 mm; slack tracked failure |
| Lechner et al., Int J Circumpolar Health 202314 | Manikin · leg trainer | C-A-T Gen 7, SAM XT and SOFTT-W Gen 4 applied over military cold-weather clothing | C-A-T and SAM XT reached the 180 mmHg cutoff in almost all applications; the SOFTT-W Gen 4 fell short in some clothing setups |
| McCarty et al., JAMA Surg 201916 | Manikin · randomized crossover | 102 laypeople trained on the C-A-T, then applying 5 tourniquet types on a HapMed trainer (2018) | Correct application 92.2% C-A-T vs 68.6% SOF Tactical Tourniquet; skills trained on one design did not fully transfer |
| Walters et al., Prehosp Emerg Care 200515 | Human · volunteers | 7 self-applied tourniquets on the thigh (n = 18) and arm (n = 12), including the original 1 in. SOFTT | C-A-T, EMT and the original SOFTT stopped the distal pulse in every subject, arm and leg |
| Kragh et al., J Trauma 200817 | Human · combat clinical series | 232 casualties, 428 tourniquets, Baghdad combat support hospital, 2006 | No limbs lost because of tourniquet use; tourniquet time not associated with increased morbidity |
| Montgomery et al., J Spec Oper Med 20199 | Expert review · evidence-based update | Review of limb tourniquets for TCCC behind the evidence-based's April 2019 vote | First update to the evidence-based standard limb tourniquets since 2005; notes the lack of unbiased data and of official evaluation criteria |
Strongest to weakest: clinical series and live-volunteer studies, then manikin studies. Only the 2023 Wall study tested this fifth generation; the volunteer and manikin comparisons that favored the C-A-T tested earlier SOFTT-W generations, and the slack findings are the problem the indicator wedge was added to address.
How it compares
The SOF® Tourniquet against its own previous generation and the two tourniquets buyers most often weigh it against.
| SOF® Tourniquet (Gen 5) | SOF® Tourniquet Gen 4 (SOFTT-W) | C-A-T® Gen 7 | TMT™ | |
|---|---|---|---|---|
| Tightening system | Aluminum windlass; TRAC clip holds it, Tri-Ring Lock™ locks it | Aluminum windlass; TRAC clip and Tri-Ring Lock™ | Windlass rod locked in a windlass clip, then a hook-and-loop windlass strap | Torsion bar that locks into a retainer with an audible click |
| Strap width | 1.5 in. | 1.5 in. | 1.5 in. | 2 in. |
| Weight | 3.7 oz (105 g) | 4.2 oz | 2.7 oz | 3.5 oz (99.2 g) |
| NSN | 6515-01-696-4522 (Black) | 6515-01-587-9943 | 6515-01-521-7976 | 6515-01-656-6191 |
| evidence-based standard | Yes — current generation of the listed SOFTT-W | Yes — listed as SOFTT-W | Yes | Yes |
The fifth generation keeps the strap width, aluminum windlass and Tri-Ring Lock™ of the listed SOFTT-W and carries its evidence-based evaluation.2,3,5 Weights and widths come from each manufacturer.3,5,19,20
Build the system
Carriers that fit it, the tourniquets it is compared with, the dressings that go beside it, and a trainer to practice on.
Questions buyers ask
Package & specifications
Available Options:
- Black
- Tan
- Rescue Orange
- Red
- Trainer Blue
| Specification | Value |
|---|---|
| Width | 2 Inches |
| Length | 5.5 Inches |
| Height | 1.75 Inches (Folded ) |
| Weight | 3.7 Ounces |
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