4 mm barrel, 2 mm gap — fits where a standard 12 mm won't
The Omron E2E-S04N02-CJ-C1 is a small-diameter proximity sensor with a 4 mm outer diameter barrel and a 2 mm sensing range on mild steel. That 4 mm head lets it drop into tight mounting holes or between machine guards where a standard 12 mm or 8 mm barrel won't fit. It's an unshielded model (the 'N' in the code), so the sensing field extends out the face and partially around the barrel — you get the full 2 mm range without needing a metal-free zone around the head. The SUS threaded case stands up to washdown and moderate corrosive atmospheres.
NPN NO output, M8 pre-wired — wiring pattern for PLC input
Output is DC 3-wire NPN normally open — the load switches on when the target enters the 2 mm window. That's the standard sinking input for most PLC input cards; the NPN transistor pulls the signal line low through the load. The M8 pre-wired connector (3-pin, 0.3 m pigtail) saves a separate cordset, but the cable length is fixed — plan the routing before the panel layout is locked.