Large impeller higher capacity water pump with a high quality die cast body. 
Fitted with a PPS, glass filled plastic impeller as used by Aston Martin and Jaguar it reduces weight on the bearing loading and has a triple lip seal giving a better controlled flow rate through the rev range.The pump is about 130 gramms lighter and has the rolled edge gasket facing evolved by Rover for better sealing. Tested with coolant pumping at 10,000 rpm with no detriment to the PPS impeller this larger impeller pump moved more coolant than the original early standard pump.
It has by-pass hose take off. These water pumps have a much larger impeller, it sticks into the block very slightly more than 1/2"(14.03mm).