Laser beams are harmful to the human eye. Never look into the laser beam directly or through optical instruments. Sensors QS18, disposable. Turck Banner's QS18 series of through-beam sensors consist of a separate emitter and receiver. These sensors should be mounted directly opposite each other so that the light from the emitter falls directly on the receiver. LED visible from all sides Reliable detection of opaque objects Excellent contrast between light and dark conditions Allows operation over longer distances and in difficult conditions M12 x 1 connector, laser class 1.