Fiberglass mat provides structural reinforcement for stronger repairs and can be used with Polyester resin or epoxy resin. The product repairs holes, cracks, and gaps. When used with polyester resin, repairs are 100% waterproof, making the products ideal for tubs, showers, sinks, pools, hot tubs, boat repair, and more. It is easy to work. Fiberglass cloth offers numerous benefits, including resistance to expansion or contraction as temperatures change. Fibre Glass Mat will not absorb moisture and is non-flammable.