Built from the same expedition weight Merino wool as the Thermo 350 Hoody, this vest gives you another option to dial in your optimal insulation . W e added a 4-way stretch Primeflex ™ shell across the upper half for increased wind protection, water resistance, and durability . You can wear it as an external layer over a Thermo 150 or Sol Tactical on cool days or use it as an additional mid-layer under a shell when conditions get bitter. If you’re serious about cold weather fishing, you know the importance of maintaining your core temperature, and that’s exactly what the Thermo 350 Vest is designed for.