The Greenbrook T41D-C Photo Sensitive Lighting Wall Switch replaces a conventional wall switch to provide timed switching of lights while still allowing normal switching operation. Hinged cover also operates as a light switch. This kind of switch is often recommended as part of a smart security plan, as when unattended the lights will still switch on at night. The delay can also be set from 1-8 hours to suit your needs. Light sensitive switch which turns the lights on when it gets dark. Adjustable Lights on time between 1 and 8 hours. Replaces existing light switch. Will still operate as a manual switch. Suitable for use with 40-400W GLS lamps and most low energy lamps 17W and above. Not suitable for use with LED lighting. Fused. 2 way switch. Dimensions: 86mm(Height) x 86mm(Width) x 27mm(Depth). Instruction Manual Comes complete with a 12 month manufactures warranty.