Abstract: A milking liner for an automated milking machine includes a barrel that moves between an uncollapsed position and a collapsed condition when it is subjected to a vacuum milking condition. The barrel defines at least three parallel channels open to the inner surface of the barrel. The configuration of the sidewall of the barrel and the channels cause the barrel to uniformly collapse when the barrel is subjected to a vacuum milking condition. In one configuration, ribs protrude from the barrel sidewall and define channels with the same wall thickness as the sidewall segments disposed between the ribs.