HK G3 HK91 PTR . ...REAR SIGHT DRUM REPLACEMENT PARTS SET................................................NEW HK G3 REAR SIGHT DRUM REPLACEMENT PARTS...2- REAR SIGHT DETENT BALL ...2 - REAR SIGHT DETENT BALL SPRING....2 - Rear Sight Elevation Plunger ...........2 - REAR SIGHT ELEVATION PLUNGER SPRING .................THESE FIT MANY OF THE HK DRUM CYLINDER STYLE SIGHTS....Correct for all HK diopter sights including: HK91, HK G3, PTR91, HK33, HK53, HK93, HK94, MP5, SP89, MP5K, SP5K, Etc.