Mad Rock Redline Climbing Shoe - Men's Synthetic Molded Compression Tongue: Used in conjunction with Arch Flex technology, Mad Rock's new tongue design locks and hugs your foot into place. The molded tab is easier to manipulate for better entry and exit from the shoe. Power Tape: Reduces the bulging issue found in downturned climbing shoes by preventing the rand rubber from overstretching. Also supports better edging performance where it's needed. Perforated Tek Flex: Mad Rock's latest upper material provides great breathability along with a little give compared to the original non-stretch fabric. Patented Concave Sole: Mad Rock's innovative and patented Concave Sole allows climbers to utilize their feet as they would their hands. Concave Soles are optimal for grabbing at holds while climbing on overhangs, and also help to create a sharper edge and better support for standing on tiny holds and edges. Arch Flex: By utilizing our 1.8mm thick R2 rand rubber formula, the Arch Flex system gives our high performance shoes an unbelievable comfortable, but glove-like fit. The elastic property in Mad Rock's R2 formula hugs and locks your foot into place without the pain associated with other high performance shoes.