On steep descents, icy winds cause your arms to cool very quickly. The X-BIONIC® ARM WARMER protect your muscles against cold and help prevent injuries. The arm loses heat differently in specific areas, so the high-tech knitting technology of X-BIONIC® insulates in specific way. Bending the elbow, a system of chambers and channels unfolds, like an accordion. The ExpansionRibs™ improve its ability to insulate rather than thinning out. The unique knitting structure extensively distributes sweat over the arm, which then evaporates and cools. Excess sweat is immediately transported away through the ARM’S Warmer. Creating perfect thermo regulation, so you can cycle with more energy.