“AVAILABLE IN TWO COLORS: CLASSIC WHITE OR MIDNIGHT BLACK The BK Valve is one of ESP’s simpler versions for a BK suspension system. This product is designed for below-the-knee patients that want auto-expulsion WITHOUT a push button. The BK Valve allows wearers to utilize suction suspension in their prosthesis instead of the old standard locking suspension. Clinicians can utilize the BK Valve with our BK/BK2 Threaded Housing (PA0222) to give the user an inner flexible socket. Releases air at 1/2 PSI without adjustments. Designed with a low profile: 7/8″” diameter.”