The Z41 Push Button Lock-Out Tailcap from SureFire provides constant-on light activation without having to rotate the tailcap on your light. Push once for constant-on, push again for off. The lock-out option eliminates accidental activation during covert maneuvers, or while in storage. This is the standard cap that is supplied with the 6P, it is also compatible with the C2 and Z2 flashlights.