Round light barriers, GR18 Inox, GRL18S-N2431V, switching distance max.: 0.03 m ... 7.2 m, sensor principle: reflection light barrier, detection principle: double lens, switching output: NPN, switching type: light/dark switching, connection type: M12 connector, 4-pin, light transmitter: PinPoint LED, setting: none, communication interface: -, included in delivery: fastening nut (2 x)