What it is and where it fits
The E3XZV412M is a fibre amplifier unit from the E3X series, designed to work with separate fibre optic cables for sensing in tight or harsh locations. It's a PNP output device with a 50 µs response time, fed from 12 to 24 VDC, and can sink or source 100 mA to a PLC input. The 2 m cable makes it a direct wire-in for control cabinets where a separate amplifier head is needed. The 10 mm width lets you pack several on a DIN rail without eating up panel real estate.
How it compares to the E3ZG812MOMS
If you're looking at a through-beam sensor like the E3ZG812MOMS, stop: this is a fibre amplifier, not a self-contained photoelectric. The E3ZG packs emitter and receiver in one 11 mm housing with a 1 ms response; the E3XZV412M needs a fibre optic head, but offers 50 µs speed. The 1 mm width difference (10 vs 11 mm) means the mounting foot is different, so you can't just swap on a DIN rail without adjusting the slot. For a fast detection zone where you need to route the sensing head into a confined area, the fibre amplifier is the right call. For a simple through-beam gap, the E3ZG is simpler.