2x ½” 15-21mm U Bolts – Zinc Plated Steel – Suitable for External installs Overview: Commonly used to secure pipework and poles to brackets, walls and chimneys, our high grade/heavy duty U-bolts are made from zinc plated passivated steel and come in various sizes and quantities. A full diagram of size specifications can be found on the picture above but if you are unsure of anything, please feel free to get in touch. Technical Specification:Minimum Diameter of pole that is compatible – 15mm Maximum Diameter of pole that is compatible – 21mm Length of thread – 30mm Diameter of thread – 6mm Made from - zinc plated passivated steelNuts are supplied as pictured