The Autobahn Dual Duro Ultra 97a Wheels is a classic Dual Durometer wheel re-invented with a harder core and outer. Featuring our Ultra formula with FlatOut technology in our standard shape and 100a hardness. This new version features a harder core for a firmer bearing seat, increasing stability at high speeds and powering through turns. Formulated to slide longer, roll faster, and never flat spot, our exclusive FlatOut compound allows complete confidence in any situation, at any speed. No flat spots, no uneven wear, no compromises.