For the redevelopment of the classic Quantum, Five Ten worked with the Huber brothers, Alex and Thomas, to develop an all-around performance shoe for any climbing setting. They started with a Stealth C4 outsole, the Hubers tackle a diverse range of climbs with many different angles and rock textures and C4 is a most versatile compound. The shoe has a stiff midsole and lined Clarino synthetic upper, so it stays comfortable for extended periods of wear. The tongue is a perforated ariaprene, which conforms to the foot and provides unmatched breathability. The Quantum is built on a new last; it is slightly downturned and a bit wider than traditional downturned lasts allowing your foot to sit in a more natural position.