Ideal Hy-Gear, Series 63 Full Size Worm Drive Stainless Steel Hose Clamps Marine grade clamp for boating applications and other corrosive environments. High nickel alloy stainless steel meets the demands of marine use. Screw: 5/16" hex-head. Corrosion resistant 300 grade stainless steel. Band and housing: 9/16" wide. 300 grade stainless steel.