Dr. Brown, what's the difference between the European version and the Crystal version?

The European version is similar to the fully transparent version, but the crystal color version is thicker.

Dr. Brown is the first functional nursing bottle designed by Craig Brown, an American doctor of medicine, and obtained an international patent on 1997. Dr. Brown's brand is to create the best feeding products to promote the baby's health and the best nutrition. Dr. Brown's natural flow Dr. Brown is so smooth _ The bottle is the first bottle with an air guide system. It imitates the principle of breastfeeding and completely solves the problems of "vacuum, bubble and negative pressure" that traditional milk bottles can't overcome.