1.Safe medical-grade Silicon + ABS. <br> 2.100% waterproof. <br> 3.Big size (203*4.4mm) will help you recover from your injury, get rid of the pain and release the tension in your entire body.<br> 4.USB Rechargeable, Built-in battery <br> 5. 20 Speed Frequiencies, 8 Power Modes<br> 6. Quiet and Waterproof. <br>