Abstract: An inflation/deflation valve for filling a dunnage bag with air includes a sleeve for insertion into an opening in a wall of the bag, a cap for covering the sleeve and threaded onto the sleeve and an inflation head for engaging the cap. A valve is mounted in the cap having a valve seat, a valve member moveable generally axially of the sleeve and a spring biasing the movement of the valve member in the axial direction toward the valve seat. The cap has mounting lugs on the base adjacent the bag arranged for engagement with co-operating slots of the inflation head in a bayonet fitting where the slots are shaped so that the head is cammed by the lugs in the slots to cause depression of an abutment surface of the valve member against the spring bias to open the valve. The removal of the cap allows rapid deflation of the bag for testing or reuse.