A synthetic jacket aims to have the warmth of down, while simultaneously performing better than down. Very few synthetic jackets can match the warmth of down, but there are definitely advantages to synthetic jackets. They compress better, they decrease bulk, they retain their insulating properties better when wet, and they don’t lose loft as much as down. Popular brands of synthetic insulations are Primaloft, Polarguard, and Thinsulate. Similar to Gore-Tex, the parent companies of these brands let other outerwear companies use their products in their own clothing.