Thats how this work . you rotate the top portion around and the brightness and focal length increase . but then it come off at the end . I read this about this product before , but its kind of annoy when you want to use this in a hurry and it become loose . would have prefer a switch . its quite compact and slip easily into you pocket . would buy again from Maglite , but not the same design . Advice : look for something else , but make sure it doesnt operate the same way as this device .