1. Adopting a wavelength of 635nm semiconductor laser. The laser line is clear and bright. 2. Self leveling and beyond the scope of automatic alarm function. 3. Emit four vertical lines and horizontal lines, plumb below point. 4. Design of the chassis circular bearing can rotate 360 degrees to instrument, make a beam of light to any areas of need. 5. Good-looking appearance, small, and easy to take. It can use indoor and outdoor(with the receiver can reach 40m).