Helix Racing Products Hose Clamps. Available in 5/16, 3/8 and 7/16. Sold in packs of 150. Helix Hose Clamps are double wire, self tensioning and Zinc-Plated. For use with 5/16 to 7/16 (8mm -12mm) outer diameter hose. Please select size from the drop down menu. Sold in Packs of 150 Please Select Size From Drop Down Menu Outer Diameter: 5/16″, 3/8″ or 7/16″ Double Wire Self Tensioning Zinc Plated Made in U.S.A.