This Drink Top fits both Pacific Baby's 3-in-One and All-in-One thermal bottles. Simply replace the bottle ring with this drink top, screw snugly onto the bottle and then it is ready to use! Close the top downwards when not in use to prevent spills, and simply flip into upright position when baby is ready to drink. The ideal age for this drink top is from 18 months and upwards. If your steel insulated cap fits the drink to loosely, please steam sterilize or place in the dishwasher top rack for one cycle for a more snug fit.