This Metabo HPT pumping unit comes with the flywheel and is a genuine OEM part. This complete unit is compatible with the Metabo HPT EC2510E model (sold separately). The Metabo HPT pumping unit with flywheel produces 9 CFM @ 100 PSI and max pressure is 145 PSI. This Metabo HPT unit mates to the 6 HP gas engine; please reference the tool manual before purchasing to ensure the proper fit and care of the unit. Hitachi has recently changed brands to Metabo HPT, same great quality, and dependability!