Induction Innovations MD99-660 Essential Coil Kit Includes 8 of the most used smaller diameter coils of varying lengths for removing stuck fasteners The coils each last for several hundred uses or more subject to use Use of the proper size coil, avoiding abrasion and overheating prevents premature wear to the coil The coil insulation is coated to resist abrasion The coils are all flexible and can be bent or separated for a variety of applications