Prime-Line 9090646 Serrated Flange Bolts, 1/4 In.-20 X 3/4 In., Zinc, 25 Pack Flange bolts feature a built in washer under the bolt head that helps to distribute the clamping load over a larger area. This "one-piece" design eliminates the need of a separate washer under the bolt head and is preferable for some applications as it can be more efficient and easier to use. A washer is still needed on the nut side unless using a flange nut. The serrations under the flange bite into the surface and help to resist loosening due to vibration. Size: 1/4 inch-20 X 3/4 inch Hex bolt with a serrated circular flange under the head Flange eliminates need for separate washer Serrations bite into surface and can help to prevent loosening Designed for use with a nut (not included) or a threaded hole of the same diameter and thread size