The E2E-X3D1-U 2M: M12 threaded cylinder in the E2E series, shielded inductive proximity sensor. NPN-NO 2-wire output with a 3mm sensing range. Runs on 10-30 VDC. LED indicator on the barrel, terminated with a 2-meter cable. This is the part number you'd spec for a quick-sourcing BOM line – it’s a standard Omron form factor.
Shielded construction lets you flush-mount it in metal without derating. IP67 rating holds up to washdown environments. Response frequency of 1kHz handles moderate-speed target detection. Nickel-plated brass body takes abuse.