Anodized Aluminum tubes with Stainless Steel hardware. Sturdy design attaches to headtube and seat tube OR rear rack.. Quick release design makes loading and unloading of boards an easy task. Designed to be easily removed and re-attached for bike use without a surfboard. Will not work with older style cantilever brakes with brake line on the headtube. Foam padding on the tubes prevent damage to your board. Maximum board weight 25lbs