... : 30l SOLAR BACKPACK BAG,Fabric: 600D shell made from recycled PET (soda bottles), UV resistant PU, 1680D nylon base, and sandwich mesh ... back, inside pockets use PET mesh Weight: 3.5 lbs (1,590 ... better air flow Shell uses 600D fabric made from recycled PET (soda bottles), which is tough, water resistant and light weight