15/32" X 3/16" Pilot Hole HSS Straight Shank Counterbore BoltsandNuts.com Radiused corners prevent damage to

Radiused corners prevent damage to a spark plug by applying force to the flat sides

STI Tap: 3/4"-10 STI

Grade 8 FINE Hex Head Cap Screws

Shoulder Diameter: 1/4"

Size m20 x 1

15/32" X 3/16" Pilot Hole HSS Straight Shank Counterbore BoltsandNuts.com Radiused corners prevent damage toProduct 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