Upgrade your Glock Gen3 pistol with the optic-ready Spare Slide from. The Slide features MOS technology for easy mounting of red dot optics and front serrations for quicker manipulations.This replacement part is a factory original from Glock. Factory replacement parts are manufactured to the exact same specifications and tolerances and use the same manufacturing materials as the original parts which guarantees excellent fit and reliable operation. Some parts may need to be installed by a qualified gunsmith. IncludesGLOCK MOS Slide with assembled internalsGLOCK MOS Cover PlateGLOCK Standard Sights