1. A6S provides 2 Rechargeable & Replaceable Batteries, which can last for about 8 hours each. 2.The internal motor of A6S is more stable and provides safer and more effective results. 3. A6S has a superior effect on collagen and elastin rejuvenation. 4. A6S provides slight vibration, to accomplish your treatment without sound. 5.Perfect customer services, without worrying how to use and quality.