Optimal water filled teether is used to soothe babies' gums when their teeth start coming in, at around 4 to 24 months of age. Because babies suck on teethers, the presence of potentially harmful chemicals on the surface is concerning. The soother can be used at room temperature, however it can provide more relief if it is first placed in the refrigerator to cool. Make sure it is clean before handing to your baby. Clean with a clean damp cloth. Before each use, inspect the product. Throw away at the first sign of damage and weakness. Do not immerse in water. Cool only in a refrigerator, do not place in the freezer compartment. Do not boil, put in the dishwasher, steam or microwave sterilize. Keep away from direct sunlight and any heat sources.