Rear sight Elevation & windage target turrets 3/8" integral mount Positive internal locks Fits Crosman air pistol models 1701P, 1740, 2240, 1377 & 1322 that have been modified with the AS2250-013 receiver kit Williams rear sights have a reputation as being top-notch. Made with quality materials, they can easily be fitted to Crosman guns that have the AS2250-013 receiver kit, which gives you a mounting rail. To increase accuracy, get this rear sight!