Why should I buy a Gigatent? Fabrics: We use materials that are heavier coated than most manufacturers. The coating on fabrics is measured in millimeters. This measurement refers to the height of a column of water that the fabric will support without it coming through. Most of our competitors use a 450mm to 600mm coating on their tents and rain flys. Our tents use a 1200mm to 800mm coating on our rain flys, because the force generated by a storm is greatest on the rain fly. We use an 800mm to 600mm coating on our tent bodies where the force is less direct and weaker. The thinner the coating the less pressure needed to push water through. Zippers: The door zipper design used most in our tents is known as a Twin Track zipper.