Non Flow Thru Chucks employ a “check valve” which seals the chuck, closing the air passage while it is not being used, and when used, it will “Flow Thru” the core on the tire valve, allowing the pressure from the hose to be transferred to the tire. When a “live” air line is used for “non-gauged” inflation of the tire, a Non Flow Thru air chuck should be used. Air Chucks are engineered and manufactured for heavy duty use and a long service life. To accomplish our high quality standards, our Air Chucks are all made from solid brass. Air chucks can be Chrome-plated for maximum corrosion resistance