Our take We don't need to tell you for the umpteenth time about merino wool's temp-regulation properties. But when a product comes along that enhances those properties even further, we take notice. That's the case with Smartwool's Intraknit line, which leverages a unique, seamless knitting technique to create more ventilation zones throughout the garment. (Bonus: The men's and women's versions have different venting patterns, to account for how male and female bodies warm up and sweat.) Tradeoff: price.
The details The 200-weight fabric plays well across all four seasons. One tester wore the Intraknit top as protection against black flies on an 80°F day in Vermont, but says her back didn't feel too clammy under her pack. A male tester who wore the bottoms during an ascent of Mt. St. Helens reports that they kept him warm during a 19°F alpine start under shell pants, but he didn't overheat as temps climbed into the 30s later in the day. The Intraknit's true-to-size fit stays in place and stretches when needed, and our testers applauded the ease of mobility for activities like casting fly rods and chopping wood. Gripe: Sorry, boys, there’s no fly.
Trail cred “When we hit the summit of Mt. St. Helens, these baselayers wicked away sweat fast enough that I didn't get too chilly as it evaporated,” our tester says.