LED: CREE XM-L2 LED U3 up to 10,000 hour lifespan Output: Steady on or Strobe mode at output 500 lumens Quick detachable weaver mount fits most 4" to 5" barrel handguns with rails. It fits handgun like G19, but does not fit subcompact ones like Baretta px4 storm, G2C, XD, P99, etc with short rail. Dimension (LxWxH): 3.1" x 1.0" x 1.1"; Weight: 2.70 oz Battery: 1x CR123A lithium (included)