Other options for the RBV-H34 and RBV-25 are for recirculating options for the blow off valves. These versions will include machined aluminum fittings to allow hose attachment for the inlet and outlet. H34 utilizes 34mm (1-1/3") clamp on nipples for the inlet and outlet. The Type 25 inlcudes 25mm (1") clamp on nipples for the inlet and outlet.