Abstract: The invention pertains to a compressed air-operated fastener driver utilizing a piston reciprocally mounted within a cylinder wherein a control valve at one end of the cylinder selectively opens and closes cylinder ports communicating with a compressed air source, and the control valve utilizes an exhaust passage and abutment cooperating with an exhaust valve controlling the flow through exhaust ports. The control valve positions the exhaust valve, and differential pressure areas defined on the exhaust valve assure closing of the exhaust ports during pressurization of the chamber during the working stroke reducing noise and an efficient utilization of compressed air.