The Micro GLX laser Sight is ideal for compact and subcompact pistols with virtually no overhang. The ambidextrous tap on/off button will not snag on anything when hosteled or carried in bag. It virtually mounts to any firearm with a weaver/picatinny accessory rail. This laser sight is only 2 inches in length, lightweight and durable with built in Weaver standard compact mount. Included is one CR2 lithium battery.