Mr. Gasket Headlock Locking Header Bolts - 3/8-16 x 3/4 Inch - Set of 12

Headlock™ 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.