The milk storage bag can keep up to 6 baby bottles warm or cold, fits most brand milk bottles like Comotomo, Philips Avent, Evenflo, Dr. Brown, Tommee, Lansinoh, Nuk, etc.(Note: If your bottle is higher than 6 inches, please remove the detachable layer) Momcozy Double Insulated Baby bottle bag is designed to store breastmilk bottles, keep bottles warm or cold. Gently used for 3 days. I preferred my other cooler to this one based on size as I was using it for pump parts, bottles, and lunch. 😅 It’s a great cooler bag, purchased for $25 on Amazon.