Earbanean wrote a review of Patagonia R.5 Top - Men's on August 10, 2006
Great light weight top. Ideal for loads of different uses. I have a black and a deep blue. Interestingly, the black is a lighter weight material than the deep blue. If you want something roughly similar in weight to a 100g fleece, then go for the deep blue. If you want something a bit lighter and more of a base layer, then go for the black. Also, the R.5 is a slightly looser fit that the other Patagonia tops of the same size that I have purchased (R1 top, R1.5 jacket, MW Capilene Zip Tee).