I have a Filson Packer's jacket. This is double layered in the main body with rear quarter access panels.This is a traditional small Game Compartment.I slip a few large trash bags in there with my USGS maps inside the bags.When done right the increased bulk is negligable. You can replicate this feature with a little sewing on almost any upper body garment.This also gives you the feature of makeshift insulation.Simply fill the double layer with cat tails, newspaper. leaves etc.<br><br>