3/8-16 x 5-1/2" Carriage Bolts, Round Head, Square Neck, Stainless Steel 18-8, Full Thread, Plain Finish, Flat Point, Quantity 10 By Fastenere Thread Diameter 0.375" Head Diameter 0.844" Head Height 0.208" Square Neck Height 0.219" / Square Neck Width 0.39" 18-8 Stainless Steel provides strength and offers good corrosion resistance in many environments.