9/16" X 3/16" Pilot Hole HSS Straight Shank Counterbore Quantity:1 Part Number: 37C800BCGSS/316

Part Number: 37C800BCGSS/316

Part Number DMS70-3030

Size 5/8"-12

They are Black and gold surface treated and the length between the chucking slot on the shank to the end of the shank is standard 3/8"

Part Number: 100C800HSBA325PL/PT

9/16" X 3/16" Pilot Hole HSS Straight Shank Counterbore Quantity:1 Part Number: 37C800BCGSS/316Product Description Counterboring is the enlargement of a portion of a hole that has previously been formed. If the counterbored portion is shallow (1 8" or less), the operations is usually known as spot facing; for example, a flat seat for a bolt head or nut. If, on the other hand, the hole is enlarged to a considerable depth, it is designated as counterboring. These counterbores are made of two piece construction, having an integral shank and