Now you have a choice of momentary or constant-on light activation without having to rotate the tailcap of your SureFire flashlight. Push lightly on SureFire Click-on Lock-out Tailcap Z59 for momentary activation, push harder to "click" the flashlight into constant-on mode, click again for off. Precision machined aerospace-grade aluminum construction, hard anodized in black. Lock-out feature of Sure-Fire Z 59 Click On Lock Out Tailcap prevents accidental activation of light during tactical operations, transportation, or storage. SureFire Z59 Click on/Off Tailcap fits SureFire Executive Series flashlights, including SureFire C3 , SureFire G2 , SureFire M2 , SureFire M3, SureFire M3T, SureFire M4, SureFire D2, SureFire D3.