This nipple is designed to fit snugly on a standard 20oz plastic soda bottle. The nipple is soft and pliable, with a natural shape for the tender mouths of lambs, kids, piglets, foals, and other small livestock. Made with a special rubber formula to prolong nipple life and improve pliability. Nipple is 0.55in diameter x 2.5in long, with a 1.38in thumb tab.