Single shot insert for an AR15 magazine for NRA and CMP high-power competition. This inserts on top of the existing follower. The easiet way is to remove the floorplate, spring and follower, and then insert this adapter, then reassemble. I also have a one-piece version.
Check out Revere's Riders for top-notch, affordable rifle marksmanship training: http://www.reveresriders.org