Flex Rating 7 (1 Soft - 10 Stiff) 3D Molded Tongue The asymmetrical tongue is 3D molded and curved towards the medial side, following the naturally raised ridgeline of your forefoot to alleviate pressure points and give a more balanced feel of comfort and support. An anatomically correct and asymmetrical tongue performs better than a standard straight one. 3D-Molded Dual Density An extra layer of high-density EVA supports the deep heel cup and anatomical arch, while comfort EVA offers more flexibility to the forefoot. Silicone top-print adds traction to the fleece-lined footbed. H4 Coiler Technology Silver Heat Moldable Liner The redesigned Silver-Level Thermo Heat Moldable liner will conform to the shape of your foot perfectly. Premolded on a FlowFit last, this liner will remain snug where it matters most, with an internal Heel Harness that will give you optimum support. This liner offers maximum comfort and performance, featuring high-density thermo N-FOAM, Nidecker's reverse-cut asymmetrical comfort-cuff and internal multi-layer latex J-bar construction. The removable harness offers easy control of tightness and support, and the Helios model adds an exclusive Velcro top power strap closure and external EVA reinforcement panels for targeted support.