Specially designed for orphaned lambs. Shaped like a ewe's nipple. The metal valve inside allows air to flow in smoothly but controls milk flow. Screws onto a plastic 2 liter pop/soda bottle.
I keep Soay sheep which are a pretty small breed. Though they tend to be VERY good mothers, a couple of times I've been surprised suddenly with a tiny, squirming bottle baby. For such tiny little mouths, this is the only teat I've been able to get them to nurse on. I've never had problems with the little ball falling out when I wash them... perhaps I've just been lucky?
I have tried all types of nipples on our nigerian dwarf kids, and the pritchard nipple is the only one that the kids will nurse from. The air hole allows constant flow for the kid while they are feeding. Great product.
We use this all the time for bottle kids. I love the fact that it's soft but yet durable to withstand the abuse the kids give it. Just make sure you have the soda bottle that works and won't leak. Different brands have different tops.