It is a professional Dr. Pen skin care kit in the comfort of your own home. This one smart investment will save you a fortune in expensive, time-consuming salon facials. Dr. Pen M5 can be used wireless (with a built-in rechargeable battery), or with the cord, both included. Simply recharge skin pen and change cartridge before a procedure. Use each cartridge only ONCE. Always dispose of cartridges after use; they are NOT reusable. Repeated use of a cartridge may result in skin irritation and other adverse side effects