Pre-engineered fiberglass swimming pools are in-mold, handcrafted pools that arrive at your home ready to be installed in your yard. The fiberglass is created from millions of interwoven glass threads covered with a polyester resin. It’s an incredibly sturdy material that’s ideal for an in-ground pool. In comparison, a concrete pool requires a steel or wooden framework that needs to be covered by a mixture of cement, sand, and water. Fiberglass is the material of choice for bathtubs, sinks, hot tubs, and multi-million dollar yachts, not to mention, airplanes, helicopters, exotic automobiles and many other high-performance products. As such, fiberglass is the best choice for the material for your inground swimming pool.