RLK29 Series, Retro-Reflective Reflex light barrier with increased range and water-tight housing for door and cabinet systems 2500V proof voltage between relay connection terminals and the device electronics Insensitive to service radio and mobile phone range interference No measurable emitted interference on all frequencies Stock No. 510-3249 has Dark-On switching, stock No. 510-3255 has Light-ON switching Supplied with Reflector and mounting accessory