Brand New 3/8" Ratio Relay Emergency Air Valve. Replaces: Sealco P/N: 110205. Reservoir Port (NPT): 3/4". Service Port (NPT): 3/8". Emergency Port (NPT): 3/8". Delivery Ports (4) (NPT): 3/8". Nominal Cracking Pressure: 4.5. This is a charging style valve for use with single (service only) brake chambers.