Abstract: The invention discloses an adaptor (10,50) for an air compressor (11,51). Adaptor (10,50) includes a manifold (14,52) having an inlet (20,74) adapted to be connected to the air exhaust of at least one air tool device (34) having an air motor connected, in use, to the air compressor (11, 51). An outlet (12,54) is adapted to be connected, in use, to the air intake of the air compressor (11,51), an air inlet (16,70) is open to ambient air and a valve mechanism (33,66) is adapted to, in use, close the air inlet (16,70) when a first predetermined pressure is reached by the air compressor (11,51).