You might hardly notice it's on but you'll be glad it's on when you notice it - Mountain Hardwear Kor Preshell Pullover - Womens

In my opinion this is one excellent underrated ultralight jacket that'll probably play a "jack of many trades" role in your outdoor quiver, particularly for those of us living and adventuring in areas with more milder climates.

Great for chilly shoulder season mornings and evenings and milder climates like here in Southern California. Simple yet versatile, almost thinner and lighter than paper, breathable, moves with you, and does provide some decent wind protection as well as a bit of warmth, although like another reviewer mentioned, it's not a replacement for a proper "waterproof" rain jacket. When packed into its own pocket it's so tiny that it is super convenient to take with you on hikes, trail runs, climbs, and so on.

One thing to note is that it's not the most durable jacket and one tip is to not wash it so often, since the 20D stretch nylon ripstop fabric (with DWR coating) feels quite THIN. Try not to make the same mistake I did. Also, the pullover version has a high collar but only one hand pocket.