Balluff's fiber optic sensors are used when a conventional optosensor is too large or too inflexible for the application. Our fiber optic sensors can be combined with either a plastic or fiber optic to create a complete sensor. Their different properties give you maximum flexibility depending on the application. Fiber optic device, light emitter=LED, connection type=plug connector, switching output=NPN normally open (NO),NPN normally closed (NC) pins 4-2