Ocean Kayak Comfort Seat: Lists for $89.95 at Ocean Kayak web site. According to Ocean Kayak, "A cushy backrest with cushioned seat pad for comfort and a drier ride. Durable foam-injected design provides sturdy support." This statement is accurate, but is not nearly the whole story.
My experience is that this seat totally transformed my experience of paddling a sit-on-top (SOT) kayak. I normally paddle a high-performance, sit-in, sea kayak, and I dislike paddling SOTs and do not own one since they are so uncomfortable for me to paddle. For some reason, even when pushing hard on the heel stops built into a SOT, my butt slides forward when paddling the kayak, which results in an extreme reclining position so that I cannot use torso rotation, which is very painful to my lower back and extremely exhausting (I become exhausted partly from the pain). However, when I visited Lake Tahoe last summer a SOT was the only kind available to rent, but all of the SOTs had the Ocean Kayak Comfort Seat installed. I was dubious, but rented one anyway. What a transformation! While the 11-ft by 32-inch kayak itself was somewhat of a barge, and weathercocked badly, I stayed in place and could use my normal torso rotation, and did not get unnaturally exhausted. Although I do not own a SOT, I plan to buy a Comfort Seat to take along when I run into SOT kayak rentals. I cannot think of any reason not to rate this item a "10".