I give 5 runs because it does what it's supposed to do. May fail if easily broken as some reviews suggest. But until then (and it will probably be my fault) the repeatability is good. .0001-.0002 in both directions turns the light on and off. The point of this review is to clarify that when I took the part out of the box I first touched it with a piece of metal thinking it would catch fire. nope Then he squeezed with his hand. nope I removed the battery and wanted to buy a new one. Put it in the machine (leave the spindle out) and it will shine brightly. user error. The documentation is not very good. The product looks as advertised.