This one is from the USA, where dairyman Garry Johnston developed the ´Milk-Easy´, to take the place of milk-cup weights or hand-weighting to milk out those slow quarters.
Just slip the Milk-Easy Spacer on top of the cup for the slow quarter, and it will be finished at the same time as the other three. The Milk-Easy is a loose fit on the cup inflation, but stays on the teat when the cluster is removed (manual or auto removal), due to the soft rubber internal tabs. It is then simply removed from the teat, and rinsed-off ready for the next use.
Using two Milk-Easy spacers is ideal for cows with heavy rear quarters, to reduce over-milking (and inherent disease risks) of the front quarters.
The Milk-Easy inside diameter is 57mm to fit over inflation top.