Fiberglass is a remarkable material. It keeps boats floating, makes bridges strong but flexible, and is even used to make large free-form architectural structures such as Saudi Arabia’s Hajj airport terminal. When used in windows and doors, its benefits are obvious to homeowners: long lasting, low maintenance, rugged and destined to outperform any other window material in virtually every way. Here’s a look at a hockey team doing its best to dent up an Integrity® from Marvin fiberglass window. These guys might be great in their league, but looks like Integrity ends up in a league of its own.