Sterex Electrolysis Insulated 2 Piece F3I needle ensures that the current is concentrated where it's most needed and at the tip. For electrolysis treatments. They are suitable for shortwave diathermy, and flash thermolysis. Available in sizes 2,3,4 and 5. Manufactured from diamond drawn medical grade stainless steel and coated with a specialist medical grade insulation material. Pack of 50.