Air Loaded Pressure Reducing Regulator, Sliding Gate Seat, High Accuracy The Mark 66/660 is a highly accurate and economical air loaded pressure regulator that provides regulation from a local station or from a remote station. Dome loading combined with the sliding gate seats provide excellent regulation and rangeability. This air loaded regulator valve can be coupled with an extended range I/P for remote operation. It can also be manually controlled with a MK12 loading station or a LowFlow JR regulator.