The Jay Xtreme 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 "Tritex" cover comes standard with this Jay Xtreme wheelchair cushion. A pair of foam wedges (the two light colored components shown on the left and right sides of the cushion in the picture above) are provided as optional adductor supports (i.e., they help to keep your legs from moving beyond the left and right cushion edges). If desired, the adductor supports need not be used. Note that the manufacturer—Sunrise Medical—recommends this cushion or the J3 cushion (also available here) as the replacement for the Jay Xtreme S cushion which was discontinued in Dec 2010.