TSR200 Aperture Sight for Ruger 10/22 Now STANDARD with Extended National Front Post – allowing for shooting at shorter ranges. 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 TSR200 allows for additional elevation adjustment at the rear sight. Uses incremental windage adjustment with rugged detent locking. Front sight tower comes with standard incremental detent adjustable type post. 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. Compatible with TS211 Sight adjusting tool and IRAS aperture inserts (not included but also available on Amazon) front sight fits standard barrel (Bull barrel is .920″ and requires adapter TS157 not included) If you have scope rails such want to use with after market installed rails there is a rail version of this sight called TSR200RL also available on Amazon. although not required or included, a handy TS211 adjustment tool is available for the TSR200. also available on amazon is the TSR100 rifle sight for the 10/22 it has a different flip style rear sight.