Much like the old Hart cups, automatic drinker cups require slightly more pressure to operate than nipples do (at least 40cm of water pressure or head), but can also tolerate higher pressures of water, (about 2.5 metres) pressure or head. Screwed into adaptors which are glued into round pipe, these drinkers use a tongue or trigger, pin and seal to control water coming into the cup. Reasonable amounts of water come into the cup when triggerred allowing other birds to learn and use the trigger. Birds adapt and learn how to use these drinkers promptly, although silkies may find them difficult to understand, silkies and polish may struggle to target the trigger or tongue on trigger drinker cups. Cup comes with seal but not the pipe adaptor/s, special adpaters are sold separately.
the 4001i is mostly (the 'i' stands for ignition, or starter) used as a Chick Drinker as the trigger is longer than the cup for adult birds, it works as a trigger in the same way but less effort required (more leverage).