Spiderwrote a review of Castelli Nano Flex Knee Warmers on March 3, 2014
Familiarity: I've used it several times
Great fabric let down but a very basic pattern which results in them not feeling perfectly flat against the back of the knee - compare the pattern of this knee warmer (basically a tube) with something like the Assos kneewarmer and you'll see why these are let down in that department. The fabric is great though, water just beads off and they keep you warm even when it gets through (stops wind chill). Wish they charged the extra and used a more advanced pattern system (which would result in more fabric wastage and a higher cost) but more comfort. The fabric has so much potential!