Manufactured in the UK by Pro-Bolt from A316 stainless steel using a single process on multi-axis CNC machining centres, which includes thread rolling. Thread standards are to BS3692:1967, the British Standard for ISO Precision Metric Threads, and route radii vary between 0.8mm and 0.4mm, the maximum that we can use to improve shear strength. Thread lead varies between K1 and K2.
A316 stainless steel has a minimum chromium content of 16.5% and contains elements of carbon, molybdenum, silicon, phosphorus, sulphur, nickel, manganese and iron, all of which add properties of formability, strength, weldability and enhanced corrosion resistance. All of the fasteners are highly polished to a mirror-like finish.