SAFETY: Adult supervision is required for children under age 3. Please inspect the brush for loose parts before use. Replace brush head after 3 months of use or if parts become loose. Small parts may be a choking hazard. Do not submerge in water - the unit can be damaged. Do not mix old and new batteries. Replace with alkaline batteries. Do not mix alkaline, standard (carbon-zinc) or rechargeable (nickel-cadmium) batteries.