Out of the individual air inlet valve 6000-VFG we build complex units for tunnel ventilation. For that, there where necessary, we leave off the upper or bottom flange and the inlets can be put together by means of positioning pins. Further details are identical to the specifications of the air inlet valve 6000-VFG so they are equipped with curved inner flap and stainless steel side arms. This unit, in this case built together out of 4 elements can be controlled by means of a special connection set.