The Smartloft Cropped Jacket builds its warmth from Smartloft insulation, a recycled wool fill made from the leftover scraps of Smartwool's own Classic Thermal Merino Base Layers. A wind-resistant front panel with a non-PFC DWR finish blocks the elements up front, while a merino wool blend lining keeps the inside soft and regulated against skin. Four-way stretch panels at key mobility zones and a cropped length keep the jacket from adding bulk under a shell or over a base layer. What Our Gearhead® Experts Are Saying:"I wore this on a cold morning that kept stopping and starting between errands and standing around outside, and I never had to zip up a heavier jacket over it. The wind panel up front did the work I expected from something twice as bulky."