Silverline - 12PCE DAMAGED BOLT REMOVER SET - 467893 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, 17, 18 & 20mm. Can be driven with a metric spanner or socket. Storage wallet included.