The Jay Xtreme S wheelchair cushion (sometimes mistakenly referenced as the "Jay Extreme" cushion) can generally be categorized as a gel cushion due to its pressure-distributing fluid-filled pouch component. Sunrise Medical—the manufacturer of this product—specifies this cushion as follows.
Sunrise Medical's "Incontinence-Resistant" cover comes standard with this Jay Xtreme S wheelchair cushion. The Xtreme S cushion cover has a built-in pocket (i.e., it is sewn into the inside of the cover) that keeps the gel pad in place. Thus, there is no need for an additional fluid-barrier which would otherwise surround the cushion (as found on the Jay Xtreme).