These spring loaded drill bit guides are self centring & are used for accurate drilling of holes for fittings such as hinges to ensure exact alignment. They can be easily dismantled for cleaning & are supplied with a HSS Drill Bit. This set comprises a quick chuck & three sizes of drill bit guides for accurate fitting of hinges. Contents: 1 x Quick chuck.1 x Drill bit guide 5/64in.1 x Drill bit guide 7/64in.1 x Drill bit guide 9/64in.