Abstract: A quick disconnect coupler includes a seal retaining member movably mounted in a coupler housing. A sealing washer biases the retaining member toward first position, and an annular seal is mounted in the retaining member. This annular seal defines both axial and radial sealing surfaces, and it is configured to transmit sufficient force to the seal retaining member to move the seal retaining member to a rearward position in response to a first, larger diameter plug bearing on the axial sealing surface, and to form a radial seal around a second, smaller diameter plug.