Marvel's electrician card level, MBL-100C, is ideal for installing switches and outlets. Three partterns of measuring; horizontal, vertical and 45°are possible. There are also three holes in the center and these are convenient for marking the center hole for hole saws. You can easily "center out" for opening the switch box with a hole saw. The thickness is only 5mm and it has very light weight(36g), so it must be convenient for carrying.