Tech Sight's aperture inserts for TSR200, TSM200, MINI200 and other 200 series rifle sights. Easily replaces the existing aperture in all 200 series Tech-SIGHTS. (SKS, Marlin, Ruger, AK, CZ, & Mossberg). Three different size inserts: .042", .062", and .086". Inserts are constructed of impact resistant urethane. Inserts are hooded and flanged to shade the aperture opening for a precise undistorted sight picture. All steel Aperture has .125" opening to accept the inserts.