The RW 1 (Assembly) is a flight proven high integrated Reaction Wheel with the following features: (1) Separate wheel drive electronics (WDE) for up to four Reaction Wheels. (2) PI controller for speed and acceleration. (3) Two different rotating masses available (Type A or Type B). (4) Four different standard data interfaces available. (5) Low level emitted vibrations, due to the mechanical design and the high level of alignments and balancing.