A tourniquet is a must-have piece in any first aid kit. The SOF Tourniquet by TacMed excels in extreme reliability and strength. Gen 5 is the latest version of this tourniquet and it features several improvements that make one-handed use easier. Made in the USA.
The SOF is supplied with an illustrated user manual. However, you should learn to use the tourniquet before bad things happen.
The latest version is somewhat lighter because many steel bits have been replaced with high-strength polymer. The tourniquet handle is still machined from a solid piece of aircraft aluminum. The tri-rings are molded Acetyl, a high-impact polymer. All the materials maintain their strength in extreme operating conditions.
Multiple upgrades make one-handed applications easier: The new buckle keeps the webbing stable at any angle you pull. The new webbing maximizes compression during application and it glides through the buckle easier. And the new Slack Indicator Wedge stitching confirms you have pulled all excess slack from the webbing.
Applying a tourniquet should be simple. Thus, SOF Tourniquet is applied the same way to an arm or leg. It is also designed to reduce the chance of accidental release or mechanical failure. The fastening system will perform reliably when soiled, muddy, frozen, or wet. The safety set screw prevents accidental release of pressure. It isn’t required to gain hemorrhage control, but it is recommended when moving the patient in a tactical environment. Dual locking rings offer a backup locking system.
The modern battlefield and mass shootings have shown that the risk of having to amputate a limb because of a tourniquet is not really an issue, while blood loss is among the most common reasons of death. This has changed the approach to tourniquets and instead of the last option to treat limbic hemorrhage, they are now pretty much the first thing you do. There's not an IFAK on the market today which doesn't include a tourniquet.
For more info, here's a clear article with dos and don'ts along with other verified info. Also check out the company's intro video.