Made of hard alloy, they are of strong strength and long durability. This is a set of 10 pieces sturdy tools to help remove nuts, bolts, screw heads, studs, etc. Fit head sized 9, 10, 11, 12, 13, 14, 15, 16, 17 and 19mm Spiral cut teeth provide a positive grip to remove rounded or damaged bolts. These tools can be driven with a metric spanner or socket for fast work. Specifications: Material: Alloy Color: Black Fit Head Size: 9mm / 0.35’’, 10mm / 0.39’’, 11mm / 0.43’’, 12mm / 0.47, 13mm / 0.51’’, 14mm / 0.55’’, 15mm / 0.59’’, 16mm / 0.63’’, 17mm / 0.67’’, 19mm / 0.74 Case Size: Approx. 17.2 x 7.9 x 3.5cm / 6.77’’ x 3.11’’ x 1.37’’ Package Weight: Approx. 368g Package Included: 1 x 10Pcs/Set Nut Remover Kit