The best thing about synthetic insulation is that it stays warm even in extreme, wet conditions. Until now, that reliability has come at the cost of bulkier and heavier products. Taking cues from one of nature’s most effective insulators — trapped air — Sitka saw an opportunity to make synthetic insulation lighter and warmer while keeping its warm-when-wet properties. Enabled by PrimaLoft, Sitka's Aerolite Collection harnesses the insulating property of air to keep your pack light and your body warm, even in the wettest conditions.