This is the electronic valve set normally supplied with the Viper but can be used in other applications too...

The valve set is quite small, measuring just 45mm at the widest point and about 30mm high so can be fitted in the tightest installations.

It actually features three valves; one pair for up/down for retracts and a proportional retract valve. There is no fiddly configuration; just plug the valves into your RX and go!