This is a complete kit with bypass block cnc machined from aluminum 6061, 10 micron fuel filter, o-rings, tee’s, hose and clamps. 

This kit will help protect your VW TDI if the cp4 injection pump has a failure. The cp4 uses diesel fuel to lubricate the internals of the pump then it sends it up stream to the injectors. This kit separates that fuel and sends into a filter and then back into the fuel tank while giving the high pressure side fresh clean filtered fuel.