Spiral cut teeth provide a positive grip to remove rounded or damaged bolts. Can also be used on screw heads and studs. Will fit heads sized 9, 10, 11, 12, 13, 14, 15, 16, 17 and 19mm. Can be driven with a metric spanner or socket. Storage case included. Spiral cut teeth provide a positive grip to remove rounded or damaged bolts. Can also be used on screw heads and studs. Will fit heads sized 9, 10, 11, 12, 13, 14, 15, 16, 17 and 19mm. Can be driven with a metric spanner or socket. Storage case included.