80g of Polartech Alpha is what’s in a Kelvin Active. I would not consider that a warm jacket. It’s great if hiking, as in pressing to get from point A to pt B. Not so great if slowly stalking through woods. Obviously layering can shift things, but I’d consider the Kelvin Active a great jacket through September. As much as I love the fit and feel, I need a layering piece that works for lower activity levels in Oct/Nov temps then I add real insulation for sitting and glassing. If I go archery elk this Fall in CO my Kelvin Active will be with me. The one light primaloft jacket I have is warmer (no idea what the fill amount is), but doesn’t breath anywhere near as well as the polartech alpha.
