Built with Iron Knee® & Seat! From ski slopes to sledding hills, we think our Squall® snow bibs & pants are the best fully-featured value out there. Waterproof & windproof they are also built with Iron Knee® & Seat. What's that? It's a double-layer of extra-tough nylon patched on the knees and seat — where snow bibs need extra protection most. Even better, Grow-a-long™ legs extend up to two inches for a long-lasting fit that lasts many kids more than one season. Easy ankle zips give them room enough to slide right over snow boots.