The WTB250-2P2431: The 100-300 mm sensing range with background suppression means you set the detection point anywhere within that band, and the sensor ignores reflective surfaces beyond it — no false triggers from a shiny roller or a machine frame behind the target. The 3 ms response time is fast enough for a line running at 200 parts per minute; faster applications (baggers, pick-and-place) need a sub-millisecond sensor. Light-ON / Dark-ON switching is selectable via the wiring or a teach-in, so you can configure it normally-open or normally-closed without stocking two SKUs. The 10-30 VDC supply covers 24 VDC nominal industrial buses; the 100 mA load current drives a PLC input or a small relay directly.
The 20 mm wide housing fits standard 20 mm bracket mounts; the 65 mm height and 43.9 mm depth leave room in a crowded panel or on a machine frame. The M12 connector faces downward or rearward depending on bracket orientation — plan the cable exit so the bend radius clears adjacent sensors. The visible red LED (650 nm typical) makes alignment visible to the naked eye: aim the spot at the target, adjust the bracket, lock it down. No separate amplifier needed; the PNP output and power share the same 4-pin M12 cable.