... 3A110, 3A120(N. O. ), 3A120(N. C. ), series air operated valve. * Exterior control, 3 port 2 position. * Port ... 3A210, 3A220(N. O. ), 3A220(N. C. ), series air operated valve. * Exterior control, 3 port 2 position. * Port ... 3A310, 3A320(N. O. ), 3A320(N. C. ), series air operated valve. * Exterior control, 3 port 2 position. * Port ... size: 1/4", 3/8". 3 Port Air Operated Valve (3A100, 200, 300 Series)