The SKF Hook spanner, size 12 - 13, is designed for easy tightening and loosening of lock nuts. They are used to secure and adjust bearings on tapered journals, adapter sleeves and withdrawal sleeves.They fit on a variety of lock nuts with outer diameter(s) 80 - 90 mm. To be more specific for locknuts: KM 12, KM 13, KMK 12, KMK 13, KMFE 12, KMFE 13, KMT 11, KMT 12, N 12, N 13 and M52x1,5, M55x1,5, M58x1,5, M60x1,5 (DIN 1804).