PVC-Free. In keeping with Madshus' ongoing commitment to protect the winter world, Madshus has introduced the best-fitting and most breathable boots yet, in a totally PVC-Free construction that lessens our impact on the winter world around us NNN Outsole. Madshus boots use the Rottefella NNN binding interface. With two guide rails and a broader binding plate, NNN offers maximum stability and control over the ski. MemBrain Softshell Construction. Madshus boots feature MemBrain softshell and hybrid constructions, allowing the boot to comfortably conform to the contours of the foot while providing durability, waterproof protection, breathability, and warmth.