I'm looking to buy a Penfield Kasson jacket and am trying to work out what size to buy. It will be either small or XS - but which one? I'm 177cm (5'10") tall and have a 38-inch chest. Does anyone have an accurate pit-to-pit measurement for either the S or XS? I've seen everything from 19.5" to 21.5" quoted for the XS, with the S being 1" larger. The current size chart for the Kasson states 52cm/20.3" for the XS (measured 1" below the pit) and 54.5cm/21.3" for the S. Somewhat confusing, since 20.3" is actually 51.5cm and 21.3" is closer to 54cm - and it isn't even a true pit-to-pit measurement. Has the sizing changed over the last few years? Aiming for fitted (over a T-shirt) but not skin-tight. I'm in Australia, so there's nowhere to try one on in store, and any returns/exchanges would involve shipping it halfway around the world.