I never thought I would need one of these until I started getting far sighted.  I bought it to mount on my scrollsaw, but I also use it to build railroad models. (I chose N-Scale before my occular decline.)  It is also  really handy when I'm digging splinters out of my fingers; I'm left with a  much smaller hole than when I just use my glasses!  I have had mine for  several years and have never had to replace the bulb yet.  The optics are  good, but as with all magnifying glasses, there is a "sweet spot"  in the center that is the most useful.  It is rather heavy and has a stiff  mechanism, so you need to get a full grip with the mounting clamp on the  edge of your table.  I had it mounted on a compter table that has a beveled  edge, and it would tend to slip off when I swung the arm around.