Headlock Locking Header Bolts M8-1.25 x 25mm Set of 12 Fits GM LS or LT Series Engines Mr GasketHeadlock Bolts eliminate the need for lock washers, Period. That's because each Headlock Bolt features 24 equally spaced, stainless steel teeth serrations that bite into and hold onto the attaching surface eliminating the need for lock washers. 12 per Package Includes Ball Head Socket Tool to Start Header Bolt Into Head 410 stainless steel Minimum 18 Inch,000 PSI tensile strength 24 equally spaced clockwise teeth Details: Emission Code: 5 Finish: