I have both my 12v and 18v flashlight bulb go out quickly on my m series Milw . flashlight . the review all state that the replacement bulb go out quickly as well . I just recieve these bulb and try they out ; the first 10 minute on a freshly charge battery I smell plastic , and after 1 hour and five minute I find lens too hot to touch -lrb- probably before that time as well -rrb- . I only check it twice as I be also watch a film . I find the reflector to be too hot to touch , and the little paper ring between bulb body and reflector come unglued . bulb spring be hot but not too much . no scorch or melt plastic . incidentally , the beam blind I when I look directly into it . I even bang the flashlight around a bit and do not lose the bulb . this puppy be go back into the van and back to work . I may replace the paper ring with a couple of neophrene washer to isolate the bulb\/reflector , and I will also definately drill a couple of hole in the botton body to facilitate convection out of the side vent hole , cool the back of the reflector . as I be a plumber , I 'll not drill hole in the top for water to get in , of course . this test be with flashlight sit vertically on bottom of battery with lens set to shine horizantally\/90 degree ; usual work position for I . April ... I be back with great news . these bulb work just great , with much use , no heat problem , etc. . I drop my flashlight 5ft from a ladder and it land on its side ; it land hard on concrete and I be concern I have crack the battery casing . no crack , bulb work fine and still do .