The XU2M18MB230KR is the receiver half of a Telemecanique XU2M-series M18 photoelectric sensor pair, supplied under the Square D Sensors & Safety brand line.
Integrator note — receiver, not pair
This listing is the receiver only; an M18 emitter on the same XU2M series is required to make a working through-beam. Spec the emitter and receiver on the same BOM line so range, response time, and supply stay matched.