HSS drill bits with spring loaded, knurled sleeve. Creates accurate, centred holes using hinges as template without damaging door furniture. Chamfered head fits into hinge countersunk holes for more stability when drilling. Sizes: 2, 2.8 and 3.6mm. HSS drill bits with spring loaded, knurled sleeve. Creates accurate, centred holes using hinges as template without damaging door furniture. Chamfered head fits into hinge countersunk holes for more stability when drilling. Sizes: 2, 2.8 and 3.6mm.