Easy to mount

The WS4 extender can be easily mounted on top of the WS4-1D, to convert it into the WS4-2D. That means that you would be able to pass from controlling a 1-door relay system to a 2-door relay one, by simply adding the extender. And the final result would look as you can see in the picture.

Dimensions: 130 x 50 x 17 mm