... ensure very high penetration rate .To secure the bit from diameter loss, the gage protection inserts have got shorter length and ... Type Available Size: 6",6 1/2",7 1/2",8 1/2",9 1/2",9 5/8",9 7/8",12 1/4",17 1 ... 7/8",6",6 1/2",7 1/2",7 7/8",8 1/2",9 1/2",9 5/8",9 7/8",12 1/4 ... 120 decibels. Main Type Available Size: 8 1/2",9 1/2",9 5/8",9 7/8",10 5/8",12 1/4", etc ...