The Super Thumb ST4 is compatible with all 10/22 style rotary magazines as well as banana style extended mags. This is Super Thumb's only rifle magazine loader other than rifles that use pistol magazine's. Because of this 22 caliber guns popularity there were a number of people who sought help with this high capacity magazine's that servera after market manufacturers started making magazines for, and in recent years even Ruger has taken part in producing.