1/2-13 x 1-1/2" Hex Serrated Flange Locking Screw - 120M PSI - Steel - Zinc Clear - UNC - Pkg of 10

Flange bolts have a wide surface area underneath the head that distributes clamping loads over a greater area, eliminating the need for washers. some flange bolts have serrated flanges designed for greater holding strength in high-vibration environments.