Stays where you put it and is good and bright.I have a Precision Matthews PM833 mill and there is some type of ring on the underside that hinders the magnets. I used some sheet metal straps and additional magnets to hold it on. However the real problem is the lack of light on the cutting surface. Yes, there is a shadow where there should be none so I had to buy a Magnetic Base spot light and between the 2 lights it works well.This works very well in general. Expect to machine a collar to keep it centered on your spindle else it can rub.Cant believe I’ve been using Mills For 20+ years without one of these. This is an absolute must!Price is irrelevant on this item, just get it and thank yourself later.I gave it 5 stars after modifying the center was to small for my mill. hole in lite 50 mm. quill on mill 53.76 mm cut hole bigger no problem I love this lite very bright .Finally, I can see what I’m screwing upGreat product.