RENTHAL TWINWALL 996/999 MODERN RETRO PURPLE HANDLEBARSRENTHAL TWINWALL 996 999 MODERN RETRO PURPLE HANDLEBARS Twinwall construction consists of two aluminum alloy tubes, one within the other Outer tube is 7010 T73, which has extreme resistance to mechanical damage and is anodized to prevent corrosion Inner tube is ultra high strength 7010 T6 aluminum and is hard anodized to resist wear from twist grip and controls Rubber seals are used to cover the ends of the outer tube to keep water and cleaning fluids