NO HURT NO PAIN. ULTRA COMFY - Exclusive Design and Material. Super Comfort. GREAT WATERPROOF - Unique Designed Structure, 2-layer Waterproof Flanges. Great Help to Enjoy Swimming Showering and Water Games. Life-changer. Safe in All Aspects - 1) One-piece design, no risk of small objects falling into the ear canal. 2) Resistant to 392°F high temperature, it won't be melted by the body's heat, and won't cause falling into deeper ear canal or sticking to hair. 【Sound Hole】Users can hear warning sounds from the environment or swim coach. MULTI-SIZE - Specific sizes for infants, toddlers, children, teens, women, men, including small medium and large ear users. Much better than One-size-fit-all. Refer to Size Chart for more details. HOW TO CHOOSE THE CORRECT SIZE - Mixed-Size First for new users. (Everyone's ear canals are different even of the same age and gender.) Wrong size would cause it falling out easily or leaking. Please read the size chart and contact us for size suggestion if necessory.