How far is it to that wall? Is that socket HOT? Is it wired right? Is that extension HOT? Before I plug in a camera, computer or high end strobes I like to check the wall circuit. My three pronged buddy tells me just that, and if not it tells me what’s wrong so I can tell building maintenance. My Fluke buddy tells me if that extension cord is “Hot” without walking back to find out it got pulled from the wall. The laser measure is used for keeping notes on big sets how far things are from each other as well as the camera from the subject. Helpful if you are working on a project where things need to be reset many times over. In total, I think I have about one hundred dollars here and they have saved my electrical connections many a time. As much as a new camera is these days, cheap safety.