Is it a retroreflective sensor?
Yes, the E3ZM-R81 2M is a retroreflective photoelectric sensor. That means it has an emitter and receiver in the same housing and needs a reflector mounted opposite to bounce the beam back. The sensing range with the standard reflector is typically several meters — enough for most conveyor and pallet-detection applications — though the exact range depends on the reflector used and the ambient light conditions. A retroreflective sensor like this is a common choice when you need a single housing to mount and aim, rather than a separate emitter and receiver pair.