Just purchased the Tau pullover and was initially unsure about the sizing (I'm 6'3", 165 lbs, 30" waist, 40" chest, 18.5" sleeve), so I bought both a small and a medium. The small fits like a glove, with the perfect waist and sleeve length, not a whole lot of extra at the sleeves but enough to maintain coverage with my arms extended. It also has enough room to fit a base layer underneath but is not too baggy that it's constantly flapping in the wind. The wind-proofing is perfect and the brushed fleece interior makes this one of the most comfortable outdoor pieces I own. I would highly recommend this pullover, regardless of the price.