I have own one of these for almost 10 year now . it be the best flashlight I ever purchase . I buy it when I be in college and work as a student Auxiliary for the college Police Department . my flashlight have suffer a great deal more then most flashlight can handle . it be be drop , run over , use as a hammer , use to pound in tent stake , constantly take on road trip , I can not even remember all of the thing I have do to it . all I can tell you be it still work .  to keep it work well you should occasionally apply a small amount of Vaseline to the thread to keep the thread and o-ring lubricate . if you do this it should last you a long time .