The Crimson Trace CMR-209 Rail Master Rail Mounted 200 Lumen Light has instant activation, tap-on, tap off. It is water resistant (IPX4) and made of polymer, fits most pistols with Picatinny (or similar), and fits using an accessory rail measuring at least one inch from recoil lug to trigger guard. Experience the power that increased illumination can provide to your defensive firearm. Introducing the CMR-209 Rail Master Universal Tactical Light for rail-equipped firearms; a best-in-class tactical light from the brand that you trust for personal protection optics.WARNING: This product may contain chemicals known to the State of California to cause cancer or reproductive harm. For more information, go to www.P65Warnings.ca.gov.