Product details:

Part #: 0000-200161. Buy as few as 1500 pcs. Discounts on larger quantities. PRODUCT SPECIFICATIONS Part #: 0000-200161 Fastener Type: Hex Flange Screw with Serration Size Description: 5/16-18 x 5/8 Diameter/Nominal Size: 5/16 Length: 5/8 Wrench Size/Across Flats: 0.491-0.500" Width Across Corners: 0.548-0.577" Head Height: 0.274-0.298" Flange Diameter: 0.686-0.706" Thread Pitch: 18 Thread Pitch Type: Coarse Thread Direction: Right Thread Coverage: Full System of Measurement: Inch Grade: 5 Material: Medium Carbon Steel Finish: Yellow Zinc Plated Head Type: Hex Flange Drive Type: External Hex Average Piece Weight: 0.0267500 lbs. Flange screws distributes holding pressure by having a circular shaped flange (external ridge) under the head so that the screw is less likely to come loose; non-serrated variety is also known as a frame bolt.