The Revolutionary Twinwall ® handlebar has a larger diameter and a double tube for greater resistance. The Twinwall handlebars are the safest and most resistant in the world. The use of two tubes makes it virtually impossible to damage and offers 50% more flexibility and amortization of vibration since their introduction in 1998, the Twinwall ® have been the handlebar of choice for the most professional racing teams and has Helped more riders to win the championships than any other handlebars in the world. Diameter A (816), diameter B (85), diameter C (43), diameter D (95), diameter E (41), diameter (179). YAMAHA yz/Yzf fold.