Polypropylene is a plastic polymer. It’s used in structural goods such as food containers and file holders, but it is also used as a fiber in diapers and mats. The Aquatread mat is an example of this. Polypropylene is highly absorbent which is beneficial for the rain, snow or any spills that may occur. The Aquatread mats are easy to clean and don’t succumb to the effects of bleach as a cleaning agent, meaning the mat won’t lose it’s color. Polypropylene in these mats also lasts about 5 years and is good for either indoor or outdoor use.