The same follower works in both STI and SV mags. These new kits use a unique locking system to keep the follower from coming off the spring. The follower and the spring have been completely redesigned for better reliability and longer life. These are a must have for any serious shooter. These will not work in the new STI 10 round mags which take a narrower spring. The follower is the same for all calibers. Only difference is the length of spring. Use the 11 coil for 140mm or less mags with flat base pads in both 38 and 40. Use the 13 coil for 140mm mags with extended base pads(7, 8, or 11mm) or 170mm mags.
IMPORTANT--- The 9mm kit is for use with a spacer ONLY. If you are not using a spacer then use the regular follower kit.
Important Info- Grams followers are designed to allow you to tune the follower to your gun and mags for slide lock. If you do not want to tune your follower and want slide lock back do not buy these followers. Without tuning they may lock back with 1 round in the mag. This gives you plenty of room for adjustment to fit your particular equipment. If you do not want slide lock back just trim slide stop tab or Follower shelf to bypass Slide stop tab.