Ruggable uses patented Cling Effect™ Technology to keep the cover attached to the rug pad. The underside of the cover grips to the top surface of the rug pad (think about how Velcro® works to keep materials together).
You can hold a Ruggable upside down and shake it and the cover will not come off. You have to manually pull it off when it's time to wash it. The strength of the Cling Effect™ does not wear off over time. Even after several washings, the cover will grip to the rug pad just like it did the first time.
The nonslip rug pad acts as a solid foundation for the cover. It has a nonslip backing and provides cushion & thickness (1/8" thick).