This is a set of 10 heavy duty tools to help remove nuts, bolts, screw heads, studs etc. damaged. or damaged bolts. The damaged nut bolt extractor is made of hard alloy, they are of high strength and long life. Can also be used on the heads screws and studs. Fits head sizes 9, 10, 11, 12, 13, 14, 15, 16, 17 and 19mm. Can be driven with a wrench or metric socket . Specifications: Type: High Case, Low Case (Optional) Material: Alloy Color: Black Package Size: 100* 100 * 50mm / 3.9 * 3.9 * 2.0in Package weight: Top case: 430g / 0.9lb Bottom case: 230g / 8.1 ounces Packing List: 1 * Screw Removal Tool Kit