zvd 3pcs hss step drill bits 4 12mm 20mm 32mm titanium taper drill bit countersunk drill bit for steel, brass, wood, plastic

size size 1 length 7 cm, meter mm from 4 to 12 4,5,6,7,8,9,10,11,12 size 2 length 7 cm, meter mm from 4 to 20 4,6,8,10,12,14,16,18,20 size 3 length 10 cm, meter mm from 4 to 32 4,6,8,10,12, 14,16,18,20,22,24,26,28,30,32. with 4mm twist drill the 4mm twist drill can pre drill the step drill, which ma