Best Mid Layer for Hiking, Backpacking, and Travel (2026)

Arc’teryx’s Delta Jacket is an ultralight fleece made from Octa fleece, one of the newer, higher-tech fleeces to hit the market in the last few years. The name comes from the octopus-like weave that creates air gaps, which helps trap heat and also allows moisture to escape. It’s very popular among ultralight brands in the cottage industry, but Arc’teryx adopted it for the 2025 revival of the company’s popular Delta fleece jacket.

I hesitated to put this jacket in this guide because, while I like it as an ultralight midlayer for summer trips, the Delta is an older, heavier version of the jacket. Judging by the angry reviews on Arc’teryx’s website, it was very popular. This jacket is something else entirely, but barring disgruntled fans of the older version, it’s a great midlayer for summer trips, especially when paired with the Sun Shirt Hoodie. At 8.5 ounces for this and 6 ounces for a sun hoodie, like the one below from Kuiyu, you have a combo that allows for multiple layering options and still weighs less than many of the more popular grid fleece options. My only complaint is that there was no focus on fashion in the design of this jacket. A user review on the Arc’teryx site compares it to Mister Roger’s sweater, which is about right. But hey, it’s light, it’s functional – who cares about fashion in the backcountry?