Abstract: A check valve which is positioned in the vacuum air line of an internal combustion engine. The check valve includes a single-piece valve body having an outlet port and two or more inlet ports, with one outlet port located substantially in line with the inlet port and connected by a venturi tube. The second inlet port is separated from the main air flow line by the valve stem and a diaphragm which allows communication there between and prevents back pressure. The second inlet port communicates with the outlet port through the valve stem and a second venturi tube which provides a vacuum boost to a device, usually vehicle brakes, connected to the inlet. The use of seal diaphragms having a non-constant radius allows for faster recovery time for replenishment than prior art devices.