needle is durable and also has high biocompatibility by applying gold plating. patient with metal allergy could also use it with not concerning contact dermatitis. non insulated needles it is possible to operate equal therapy to epidermis layer and dermis layer as the needle do not have insulation plating. stepping motor type different to existing solenoid type, the needle inserts rf energy can well to penetrate to the dermis, stimulate collagen protein hyperplasia, not only is the way to improve the scars, but also long-term tightening skin wrinkles induced the good the needle structure is easy to penetrate the skin with minimum resistance.syi