Using the proven Excal lamb teat in our 'Topper' cap. This nice solid cap incorporates a ball valve to allow inlet of air. The Topper will fit all standard 28mm o.d. thread plastic 'coke' and soda bottles. The Excal Topper is a long-lasting teat, that will rear quite a few lambs without breaking up. And lambs love it. If you wish to speed up the flow for stronger lambs, just extend the tip x-cuts slightly.