Clip on nipple rubber metallic.
It is used for pinching the nipple
rubbers before connecting.
It prevents damage to the udder tissues, as it makes it possible to control the release of the quarters from milk and timely block the effect of vacuum on the milked teat.
(//tractor-service.com)
Also, the nipple rubber clamp makes it easier to attach milking cups without losing vacuum pressure.
The clamp consists of a metal body and a plastic roller.
The stroke of the roller is 5 cm.