This Fabric Book Repair Tape is made of a 11.5 mil waterproof cloth with a flexible adhesive and release liner. The heavy weight 11.5 mil premium tape has a 40 lb tensile strength and release back liner. Binding repair tape is ideal for long-lasting hardback book spine reinforcement and repair. Available in many colors, making is great for color-coding files and storage boxes as well. The strong and flexible adhesive will not dry out, lift or bleed. Waterproof vinyl coating adds to the durability.