Premium Marine Grade, all AISI 316 (high tensile strength) Stainless Steel "HD NON-PERF" Worm Gear Hose Clamp. The 11.7 mm (1/2") wide band is Non-Perforated and Smooth on the inside with Rolled Edges. This eliminates hose damage with increased clamping force. The one piece 16mm (0.63") wide Housing provides one of the highest clamping force ratings of any worm gear style clamp. 7mm Screw head. Size 64 Min 3-7/16" Max 4-3/4" Hose 3-1/8" - 3-1/2" Band 1/2"