he TSR 100 is a adjustable sight similar to the ones used on GI rifles. Turns your Ruger 10/22 into a low cost training rifle. Currently used by many nationwide in the Appleseed rifleman training program. FEATURES: 8" Longer Sighting Radius Rear Sight Base mounts solidly to the rear of the receiver utilizing the existing tapped scope base holes. the TSR100 comes standard with dual apertures (.062) apertures. Uses incremental windage adjustment with rugged detent locking. Front sight tower comes with standard incremental detent adjustable GI type post. (Scale lines in photo were colored in for illustration purposes) Made with steel parts. Will not work on a 10/22 Tactical as it has non-removable scope mount rail. All Standard 10/22s work. Bull barrels are .920" and requires adapter TS157 (not included) optional adjustment sight tool TS155 (not included)