Built with a robust, waterproof outer layer and a removable, Thermoball insulated inner layer, The North Face?s Thermoball Triclimate Jacket keeps you warm from summer to winter, then back to summer again. The 2.5-layer, DryVent shell keeps you dry during summer rainstorms, and the insulated midlayer stands alone as a warm layer to wear during autumn and spring. The insulated midlayer and shell zip together making the combined pieces a warm, waterproof, winter jacket. Filled with synthetic insulation, this is The North Face?s only three-in-one jacket with a Thermoball insulated midlayer. Primaloft Thermoball synthetic insulation acts similar to down feather insulation by being packable as well as having an incredible warmth-to-weight ratio. It also comes with the added benefit keeping the insulation in usable condition if you?re caught in a rainstorm with just the midlayer on.