What Our Gearhead(R) Experts Are Saying:"This is one of those layers I don't think twice about grabbing. It's soft enough to wear all day, but the UPF and moisture control really matter once you're moving."We wear the Butter Up Long-Sleeve Top on bright trail mornings, exposed ridgelines, and days when the sun never quite lets up. Mountain Hardwear built this layer to feel easy against the skin while quietly handling sweat and UV exposure, so we can stay focused on moving instead of managing layers. The lightweight jersey fabric provides UPF 50 protection and wicks moisture as effort builds, while anti-odor treatment keeps it feeling fresh over repeated wears. Low-profile thumbholes add coverage when needed, and the fit stays close enough to layer comfortably under shells or insulation.