Some puffer jackets are filled with down, but many are filled with synthetic insulation that is lighter than down while still providing the same warmth.Because synthetic insulation does not clump or break apart as much as down insulation after washing, it makes a superior work jacket.Puffer jackets receive their name from the pattern of stitched portions packed with insulation to give them that “puffy” appearance. Its “puffiness” can vary depending on the quality, density, and loft .