Abstract: A teat cup liner is disclosed that includes an attachment section having an opening therein, a barrel joined to and in fluid communication with the attachment section, and a tube section, joined to and in fluid communication with the barrel. The barrel includes a transition section and a triangular section. A combined length of the attachment section and the transition section is (i) from 5.5 to 8.5 cm long, (ii) an average teat length (after elongation), optionally minus a minimum uniform pressure length, ±20%, or (iii) 40-65% of a combined length of the attachment section and the barrel. Alternatively, the transition section has a surface with a slope of less than 0.3, where the slope is defined by a change in the radius of the barrel in the transition section relative to the length of the transition section. The tube section includes a connection mechanism.