Keeping it simple is a major reason the RX 100 is so successful. PU Dual Core Technology provides power and precision by allowing the shell to have different densities of plastic in just 1 mould. A close fitting rearfoot, 100mm forefoot and roomy toe box means there\'s exceptional hold without the crushing pressure associated with some boots. The 100 flex is firm but not tiring, the liner is pre-shaped and custom moulded for the best fit and there\'s plenty of adjustment on the cuff to suit various leg shapes.