The castelli nanoflex knee warmer is ideal for those cold mornings when you need a little extra warmth without having to stick a pair of full length pants on this way you can slip off the knee warmers quickly as the day heats up and stuff them in your pack to use again later if needs be the knee warmers helps and offers protection against the elements and even if you come off your bike there is a little protection there too the nanoflex uses the water resistant nanoflex fabric that is ideal f