Step It Up. Replacing your M600DF or M640DF Dual Fuel Scout Light's rear push-button cap assembly with the UEE rear cap allows you to attach a SureFire tape switch for even greater versatility. The UEE is also compatible with the SureFire BSL-A Ballistic Shield Light for users who prefer to run a tape switch only. Made from aerospace aluminum, Mil-Spec Type III hard-anodized, and gasket-sealed to repel moisture, the UEE is built to thrive in the harshest conditions. It is available in Black or Desert Tan.