Used once or twice! Works well! Sanitized! ( 810nm is the specific absorption wavelength of melanin in the skin.) - More Precise The 810nm laser offers precise targeting, as it is primarily absorbed by melanin, minimizing skintissue absorption and reducing the potential for side effects. - More Powerful DermRays laser hair removal has up to 50% higher energy density compared to leading IPL brands on the market, resulting in more efficient hair removal.