Using these Izipizi sunglasses is easy. Just place them gently on your child's face and adjust the silicone strap for a comfortable fit. When your child is not wearing them, you can use the strap to attach the sunglasses to their clothes so they don't get lost. As for maintenance, clean the lenses with a soft, dry cloth. Avoid using harsh chemicals or abrasive materials as they can scratch the lenses. Keep the sunglasses in a cool, dry place when not in use. Make sure to check the fit regularly as your child grows. If the arms or strap seem too tight or loose, adjust them accordingly. Also, remember that these sunglasses are for kids aged 3 to 5 years, so make sure they are used by the appropriate age group.