Automatic filling kit for clean water tank. The kit allows the machine to  connect to the clean water source using some special couplings supplied with the hose. 

For the IdroFoamRinse models, this is the hose used to connect the machine to the water network, in order to let the machine work.

For the models with a clean water tank, this hose allows to fill in the tank automatically, keeping it always full. the floater inside the machine controls the filling level.