Carbon Steel Materials Made of high quality carbon steel. Small size, easy to carry. Used to check tightness or looseness of power drill tool. Thumb Grip Styles Designed for performance. Thumb grips increase leverage and user comfort. Mild steel handles limit the potential for dangerous breakage under excessive load. Easy to use Spare key with black surface. Suitable for checking the tightness of the loose of electric drills. Durable and practical Will check the tightness of the set of the electric drill clamping tool. On all common drills with toothed crown. Can be used in hammer or drill mode, very durable, comfortable to grip. Application Suitable for most drills and other power tools. Ideal for home improvement projects. Ideal for use with hammer drills where a tight fit is required. Ideal for garage, workshop, carpentry, auto parts, specializing in machine repair.