What you're getting
The Omron E3X-NL11 is a photoelectric amplifier — the signal-processing module that sits in the panel, connected by fiber-optic or separate cable to a remote sensor head. It's the amplifier half of a two-piece detection system, not a self-contained photocell. Listed under Omron's photoelectric sensors category, it's meant for diffuse, through-beam, or retroreflective setups where the head needs to be small or the electronics need to be away from heat or washdown.