I strongly recommend these bottles. Our baby had acid reflux, she breastfed for 3 months and these were the bottles we switched her to, she didn't have any problems with them. I liked that they didn't trap any air bubbles. They have extra pieces so it did require extra time to wash them but it was worth it. We kept up with the recommended way of cleaning however overtime we did notice the vent changed colour but the company sent us a few replacements for the first time, we didn't need to purchase a second time because we weaned our baby. We also had the 4 ounces wide neck ones and they worked great as well in reducing colic. Our overall experience was a positive one and I recommended them to my mom to be friends.