What Our Gearhead(R) Experts Are Saying: "I've been using the Crater Lake Heavyweight Half Zip Hoodie as my go-to baselayer for winter hikes and tours. It's thick enough to keep me warm on its own but still breathable and super comfortable under a shell. The fleece backing and half zip really help regulate temp when I start moving hard."Built to handle cold conditions and high output, the Mountain Hardwear Crater Lake Heavyweight Half Zip Hoodie redefines what we expect from a baselayer. With a cozy fleece-backed interior and a smooth, stretchy outer face, this heavyweight layer keeps us warm during frigid trail starts and mountain missions without compromising mobility. Whether we're layering under a shell or wearing it solo on chilly mornings, it hits the perfect balance between performance and comfort. The Crater Lake's slim fit pairs easily with outer layers, while the three-piece hood adds extra protection when the wind kicks up. HeiQ Mint odor control keeps us fresh on multi-day trips. Low-profile thumbholes keep sleeves in place under gloves, and the deep half-zip lets us quickly dump heat as we warm up.