The GG&G Mossberg 590 Magazine Extensions are easy to install as long as you have a working knowledge of how to break down your shotgun to perform maintenance procedures. They attach without modification to the shotgun. These two and three shot Magazine Extensions use the factory follower or you can purchase a GG&G Enhanced High Visibility Follower
here. In addition, you can purchase the GG&G Mossberg 590 Barrel Clamp
here.