Lightweight and versatile, the Flyweigh Jac-Shirt delivers warmth and comfort as both a mid-layer or outer layer. The 100g of PrimaLoft® Gold Insulation with Cross Core™ technology utilizes the power of aerogel to deliver unprecedented lightweight warmth and temperature regulation. A sleek, minimal style allows the Flyweigh Jac-Shirt to be worn as a versatile piece in the field or as everyday wear.