What this slot sensor is and where it fits
The Omron EE-SPX305-W2A is a through-beam optical slot sensor with a 5 mm aperture, designed for part-present detection in automated assembly, packaging, and conveyor lines. It runs on a 5 V supply and switches an NPN open-collector output to ground when the beam is interrupted — Dark-ON logic, meaning the output transistor conducts when an object blocks the slot. The chassis-mount body with wire leads suits panel wiring inside a control cabinet, but the -10°C to 55°C ambient range keeps it indoors; no freezer or unheated warehouse floor.
EE-SPX613 — the selectable-output sibling
The closest functional peer is the Omron EE-SPX613, which shares the 5 V supply and 5 mm slot but offers a selectable Dark-ON/Light-ON output. The EE-SPX305-W2A is fixed Dark-ON — if your application needs Light-ON (output conducts when beam is clear) or field-switchable logic, the EE-SPX613 is the drop-in alternative. Same chassis-mount footprint and wire-lead termination, so no rewiring for a swap.