Perry Mackin's Silicone Bottle is specially designed with an innovative air vent system to prevent common issues of colic, gas, and reflux by eliminating air bubbles in the milk and its breast-like shaped soft nipple secures a good latch during feeding. Our extra soft high-grade silicone nipples are as familiar to the baby as mom's breast to provide the perfect solution for switching between breast and bottle. 6 oz measures 5.75" x 3" x 3". 8 oz 6.75" x 3" x 3". Weight - 0.5 lbs.