E-Z Nurser prevents "gulping" and helps calves gain weight faster right from the start. The bottle fashioned of a special plastic with pint markings won't crack or break and lasts indefinitely. It's light and easy to clean and sterilize. E-Z Calf Nipple is rubber with cross-cut opening for full flow and air hole which prevents vacuum. Complete Nurser include 2-quart bottle screw-on cap and calf nipple. Wt. 12 oz.