Nordic Components (nordiccomp.com) are a well-established manufacturer of firearm components and produce the well-known MXT shotgun magazine extension tube and clamp.
The clamp is the de facto standard equipment used by a large number of competition shotgun users, however mostly due to user error, it does have some drawbacks. These include scuffing of the barrel and magazine extension, and over tightening.
We have produced a simple yet effective gasket that is extremely resistant to heat and chemicals. It offers protection from scuffing and vastly reduces the risk of distortion caused by over tightening.