The Olight Remote Pressure Switch for the M20 and M21 MOMENTARILY activates whatever mode the light has been set to and is made to be used with any long gun - rifle or shotgun (not for pump action weapons). Made to be fit into the integrated pressure switch pocket of a foregrip the pressure switch can also be attached with hook and look (not supplied) to any weapon that does not have an integrated pressure switch pocket. Light & foregrip not included.