The SICK WS/WE100-2P4439 is a through-beam photoelectric sensor from the W100-2 series, with a 3 m sensing range and PNP output. It switches at 500 µs, handles 100 mA load current, and works across 10–30 VDC. The body is 11 mm wide, 31 mm tall, 20 mm deep — fits tight DIN-rail or bracket-mount spots.
3 m through-beam range means the emitter and receiver must be aligned across that gap — good for conveyor belt presence, pallet detection, or part-in-place at a machine station. The 500 µs response catches fast-moving parts on a moderate-speed line; if you're counting small parts at high throughput, check whether that latency stacks with your PLC scan. IP67 means the housing and optics survive washdown — suitable for food-and-bev lines, outdoor conveyor transfer points, or anywhere hoses hit the machine. The M8 male connector (4-pin) means you pull a pre-made cable, not hard-wire into the sensor; keep a few M8 cordsets on the van. Light-ON / Dark-ON switching is selectable, so you can set it to output when the beam is made or broken. That's one less converter block in the cabinet.