The STK Tac Light is a universal illuminator for use on any firearm. With an integral Weaver mount it is easy to install. The mount includes a locking cross bolt that sits in the cross-cut of your Weaver rail to prevent sliding. This unit provides significant illumination efficiently for reliable target identification in low light settings. The STK has dual settings for flash illumination or full-on use. The lamp assembly is produced by SureFire, USA based on a high-powered xenon lamp design. This high-powered illuminator provides illumination out to 100 meters. It uses two regular 3V lithium batteries (DL 123 or CR 123) available at any Wal-Mart or Radio Shack. It is rated for extreme temperatures and installation and removal can be done in under 4 seconds using the light's integral quick-detach system. This is a great unit in every respect.