Philips Avent Natural Glass Baby Bottles with Natural Response Nipples (Slow Flow, Flow 2), 4oz, 4-Pack, SCY910/04

"5.0 out of 5 stars" - We switched from Dr. Brown’s bottles to these and have been very happy with the change. Milk only flows when the baby actively sucks, which has dramatically reduced leaks, mess, and wasted milk.The nipple design feels very natural, and our baby transitioned easily between breastfeeding and bottle feeding. One thing to note: coming from Dr. Brown’s Level 1 nipples, we did need to switch to a Flow 3 nipple with these bottles for a comfortable feeding pace.The only minor drawbacks:• At around $10 per glass bottle, they’re on the expensive side, though most comparable bottles in this category are similarly priced.• Protective sleeves are sold separately and add another $3–$4 per bottle.• The nipple ring threads are generally fine but occasionally need re-threading to sit perfectly.Overall, these are excellent bottles. Despite the cost, the performance, reduced milk waste, and smooth breast-to-bottle transition make them well worth it. Highly recommended.

"Disappointing" - They came without a box in a plastic bag. Not sure if they are authentic or used ones. There were some stains too.