The SureFire CSM-09 is a compact remote switch that allows users to activate their SureFire WeaponLight without removing their support hand from the rail. It's designed for use on M-LOK accessory rails and features a single switch that controls both momentary-on and constant-on modes. The CSM-09 also helps to conserve rail space, which can be useful if the user has a variety of rail-mounted accessories.