1/2" Class 300 Flange Bolt Kit ASTM A307 Grade A Zinc$0.00PriceOut of StockComplete Class 300 flange bolt kit for 1/2" ASME B16.5 flanges. Contents: (4) 1/2"-13 × 2-1/2" ASTM A307 Grade A Zinc-Plated Hex Machine Bolts and (4) 1/2"-13 Zinc Finish Hex Nuts.