1 x 6082 Aluminium billet 
1 x 210mm dia x inside dia 170mm x wall 20mm x 43mm thick 
6082 aluminium is a medium-strength, corrosion-resistant alloy that's part of the wrought aluminium-magnesium-silicon family. It's often used in structural applications like bridges, trusses, and cranes. 
Maybe longer, never shorter