For our "Ultra" range of polytunnels, we've used an whopping 38.1mm diameter tubing for the hoops, ridge and corner struts. The steel is high tensile "Z35" grade which is galvanised and has a 1.5mm wall thickness.For the foundation tubes we've made sure that strength and corrosion are definitely not a problem - The tubing used has a wall thickness of 3.25mm and is hot-dip galvanised.For our 12ft wide range, the polytunnel hoops are spaced at 6ft apart - a close spacing when you consider the tube size.As with all our polytunnels we've made sure there are no weak links and each component is designed to ultimately fulfil it's purpose.Quite simply, we doubt you'll find anything stronger!
See below for a detailed specification.Click here for 12ft "Ultra" Assembly Instructions 
