The Omron E2B-M12KS02-WP-C1 5M is a shielded M12 inductive proximity sensor with a 2mm sensing distance, NPN normally open output, and a 5m PVC cable. It's rated for flush mounting so you don't lose detection range when embedded in metal.
Shielded construction allows flush mounting in metal. NPN output is current-sinking; the normally open action means the output is off until a ferrous object enters the 2mm window. The M12 threaded barrel is short-body (shorter than standard), which helps in tight spaces. The 5m PVC cable gives you reach to the controller without a junction box. PVC is fine for dry, non-oily environments; if cutting fluid or coolant is present, consider a PUR cable variant.