The Varilight white plastic dimmer range has a 15mm depth from front to back of plate and requires a 25mm wall box. Covered by the Varilight 10-year guarantee. Each dimmer has different characteristics and load requirements which are listed in the product title. Single plate size: 85mm x 85mm. Double plate size: 85mm x 145mm. This is a 1-Gang Matrix Kit for Rotary Dimmers with a Twin Plate. The Varilight Matrix system allows total dimming flexibility, enabling you to create any combination of dimmers imaginable. It is made of durable white plastic.