The TRUGLO XR25 Red Dot Sight features a 25x17mm multi-coated objective lens, which is an optimal size for a clean sight picture, as well as not too big to obscure your surrounding view. Comes with a picatinny rail mount, for a primary or back up optic on your AR-15. Digital push-button brightness controls adjust the 10 different brightness settings. Compatible with optic-ready pistols.