The MEPRO TRU-DOT Adjustable Day and Night sights are for those who demand greater accuracy. Windage and elevation adjustments on the rear sight allows you to compensate for windage, elevation, bullet weight and distance when zeroing. Front sight is fixed and cannot be adjusted. TRU-DOT adjustable models offer a handgun sighting system for improved rapid instinctive aiming which requires no transition from day to night use. Day and night, the shooters aiming reference is three solid dots, identical in appearance and location under all light conditions. Designed as replacement parts for the standard weapon sights, Meprolight's Self-Illuminated adjustable night sights can be mounted directly with minor modifications. Glock 17/19/22/23/24/25/26/27/28/31/32/33/34/35/37/38/39/42/43.