A valve for use with a prosthetic socket includes a body defining a first opening, a second opening adapted to be in fluid communication with the socket cavity, and a passageway formed between the openings. A membrane is flexibly seated on the body over the first opening. The membrane is moveable between a closed position in which the first opening is sealed such that fluid communication between the first opening and the second opening is inhibited, and an open position in which the first opening is unsealed such that fluid can flow through the passageway. The membrane includes a first part connected to a release element that is operable to move the membrane between the open and closed positions, and a free part operable independent of the first part to move the membrane between the open and closed positions.
