The Twinwall, in KTM orange design, combines two handlebars in one: An exterior guarantees maximum strength against external damage (e.g. falling over) and is also anodized against corrosion. The interior, made of a special alloy, is also hard anodized to protect it from damage by the handlebar controls.
Nylon inserts in the inner tube allow thinner walls; this saves weight and has a positive effect on the flexing properties.
Rubber seals at the crossing points of the two tubes to prevent the ingress of water, dirt, cleaning agents, and other contaminants.