The CD-Y41 is an active infra-red motion detector. It senses changes in heat via its Fresnel lens to detect human movement. The sensor can detect even the slightest movement in the detection zone.

The unit is designed to be fitted flush into ceilings. 360° sensing is assured via its heat sensor. A 15 minute maximum time setting will reduce the possibility of the lights being extinguished when somebody is present. A built-in light sensor facilitates daylight harvesting.