Single-beam safety light barriers, L21, L21S-21MA2A, System part: Transmitter, Safety level: Type 2, PL c, SIL1, SILCL1, Range: 16 m, Diameter: M18, Light transmitter: LED, Light type: Visible red light, Optical axis: Axial, Housing material: Nickel-plated brass, Connection type: Plug M12, 4-pin