I got one of those a year or two ago for my dad who's an electrician. I thought the laser might be useful for cutting holes in new circuit breaker panels. I thought he could use the magnetic base to attach the laser light to the opposite side of the panel and center the laser where he needed to drill the guide hole for a metal cutting hole saw. It didn't work because the laser on button had to be held down the whole time. It didn't stay on when pushed making it totally useless for that need. The l.e.d. light did stay on when pushed which made me even more annoyed.