The WB45 wall boxes allow surface mount installation for any 45 x 45 mm standard sized product such as matrix control panels, volume controllers, connection plates, ...They come including a metal subframe(s) and are available in single (WB45S) and double (WB45D) unit size. They are available in black (/B) and white (/W) The WB45S/FS is a flush mount box for stone or concrete walls, The WB45S/FG is a flush mount box for hollow walls