I have use these light for many year now . as a musician , I find they invaluable backstage to help get cable all hook up in the dark . in fact , I have a blue and red one and I swap the part around . I have since lose one of they and now I have this hybrid red\/blue light : -rrb-  Anyhow , after a while , the thread start to get full of aluminum dust and debris and the o-ring need some lubrication -lrb- I have most recently try some chapstick and it seem to work . I have notice newer light have some kind of oily material on they -rrb- .  I would like to see they offer a lght use 3v lithium cell technology and a brighter bulb with fewer dark spot .