I've owned the Montane Aero Windshirt since my thru hike of The Appalachian Trail 07 and love it for trapping body heat and cutting wind when needed, while breathing very well and resisting light rain too. For just 3.5 oz it rocks! My best ultralight investment to date...NOW I purchased the Montane Featherlite Pants for my thru hike on the New England Trail (500 miles in 5 weeks from the NH/Canadian Border, thru MA & CT, Sept/Oct 2009. Hiked through lots of wet chilly days, typically in the mid to high 30's by day, lots of drizzle and light rain, occasionally heavy rain; If it warmed >50F and the rain stopped we hiked in shorts. I typically hike in shorts through most rain unless its cold & sustained rain and <50F outside. This trip was different. We hiked almost continuously in rain/wind pants. My Montane Windpants were the bomb! They resisted light rainspray & tons of wind. Even better is I usually kept them on while hiking even after the rain stopped. This is unusual for me, but since they breathe SO much better than most rainpants I own they were very practical. The ankle zips made donning/removing them over my trekking shoes so easy and practical - it took just a few seconds allowing the freedom to adjust my clothing system on the fly, based on changing weather conditions. It just doesn't get any lighter weight at 4oz! They proved durable enough for this trek and still look great. (Obviously I was cautious, but even did a little bushwhacking); Clearly they are not suitable for true winter conditions or when lots of abrasion is expected, such as winter glissading downhill on your butt. Note they DO wet through in heavy sustained rain (just like my windshirt) but as soon as the rain stops they dry in a flash. I Highly recommend the Montane Featherlite pants as part of a SUL hiker's wind/rain resistant clothing system.