Blister Guard is a trademark of Friction Free Technologies, Inc. Blister Guard is used in the high stress areas of socks which helps to reduce friction against the skin. To be sure that your socks have the Blister Guard, look for the Blister Guard logo on the package. Blister Guard Military Boot Socks are the ultimate military boot sock. Fox River Socks - Military Fox Blister Guard Liner Sock. A must have. Wear alone, or under another pair of socks. Great as a dress sock. Military Wear-Tested.