Reflector and mounting accessory. 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') 510-3249/ has Dark-On switching, stock No. < 510-3255') 510-3255/ has Light-ON switching