I love this vest. It is feather-light, yet blocks chilly breezes as well as my much heavier vest, while keeping my back vented and comfortable. Initially I bought the wrong size--a large (I'm 5'10"). Luckily RealCyclist had an xxl in stock & bent over backwards to facilitate the exchange. As Krikken says, it's easily rolled and stored when you take it off.
Great product, great store.