Bio-Therapeutic BT-micro Ultrasonic Exfoliation. Excellent Condition, CleanClean, used a couple times. Working Good. The bt-micro has 4 pre-programmed modes with high and low options: Exfol Mode (Exfoliation) The Exfol peeling function combines high speed (24,000 hz) ultrasonic vibration and a peeling probe to create a gentle cavitation-like effect within the skin tissue, effectively removing congestion to prime the skin for product penetration. Serum Mode (Penetration) After exfoliation has been achieved using ultrasonic waves, the Serum function uses microcurrent and ultrasonic technology to push applied serums deeper below the skin, maximizing their effectiveness for deep nourishment. Cream Mode (Penetration) After exfoliation has been achieved using ultrasonic waves, the Cream function uses microcurrent and ultrasonic technology to push applied creams deeper below the skin, maximizing their effectiveness for deep nourishment. Clear (for acne) The optional Clear function uses negative ionization to decongest pores, preparing the skin for topical applications. It pushes out black heads and debris for a truly purifying cleanse.