599630 Disclosed is a double walled teat cup liner that is inflated to provide a milking action. The teat cup comprises a mouthpiece having an open top and a tubular side wall portion that is adapted to mount to a teat cup shell. The tubular side wall portion further includes a vent hole that is adapted to admit a controlled amount of ambient air into the mouthpiece of the liner. An inflation barrel connected to the mouthpiece and adapted to receive a teat when the barrel is in an uncollapsed condition and to close onto the teat in a collapsed condition. The barrel has a multi-sided cross-sectional configuration that forms at least three air passages along at least a portion of the length thereof from the mouthpiece through the barrel for flow of air from the mouthpiece through the barrel when the barrel is in the collapsed condition to facilitate air and milk flow to and through a region beneath the teat to a milk tube.
