This pattern main body is done with a double strand. Because of that and the wool yarn and felting, the bag becomes very resistant to moisture and weather and even lends a big of insulation. I often store my lunch and the days supply of cold drink in the main body and the drink is still cold enough to drink in teh early afternoon. Lots of storage here so you have room for everything from your book or e reader to your cell phone and even an IPod within easy reach. This is the purrfect design for the traveler or the commuter.