Abstract: An all-plastic check valve is incorporated into a molded plastic surgical or medical device. A tubular arm of the device serves as a barrel of the one-way check valve and has a unitarily molded seat or sealing ring and a plurality of protuberances or keeper bumps. A hollow cone-shaped or bullet-shaped stopper permits fluid flow in one direction, but in the back direction lodges against the sealing ring or seat. The material of the stopper is softer than the material of the tubular portion. At least limited flexing is possible without breaking the seal.