The RMS2 is small enough to fit discreetly on any gun, tough enough to withstand the harshest recoil and light enough that you wont even feel its there. The RMS2 is machined from strong aerospace-grade aluminum. It has super-fast automatic brightness adjustment to adapt to your environment allowing you to concentrate on the target. By removing the battery drawer from the original RMS they have improved the overall strength of the sight and allows them to fit all new electronics to provide a clear, best in class shooting picture. Its stunning, low profile design makes it an ideal optic for any custom pistol build, and their matching low profile Glock MOS plate, has the RMS sitting so low that the sight will co-witness without the need for suppressor sights. And all this at a highly competitive price. The Glass Edition has an all new scratch-resistant ultra clear Glass Lens, and upgraded electronics with improved battery contacts with the same frame and low-profile that allows you to co-witness with standard iron sights.Features :Parallax FreeOne 3V Lithium Battery, Cr2032Housing Material: AluminumCompatible With Night VisionScratch-Resistant Ultra Clear Glass Lens4Moa Dot