AIRE's 12" diameter Kayak Thwart Backrest ($89) can be used in any AIRE or Tributary kayak, but you can also install it in kayaks from Hyside, NRS, Maxxon, and other makes with bail holes that run along the floor edges. Of course the Hyside Padillac and NRS MaverIK already come with this type of backrest, but in case you lose one or own an NRS Bandit this is an option. The price hardly makes it a bargain, but it does have a Leafield valve, which will match any American made AIRE model, and a urethane bladder, not vinyl. There are dual straps on each side so you can secure it from two directions just like the standard AIRE Cheetah Chair. It also has the same flip strap as the Cheetah Chair (see the text in the Cheetah Chair description).
The main reason paddlers buy the AIRE Thwart for their kayak is to achieve more rigid back support in heavy whitewater, and some feel it interferes less with their elbows. We don't push them one way or the other, but the demand seems to be increasing each year.
What about using these for self supported multi-day trips? Personally, we think a large, well stuffed drybag is a better bet. For one thing, laid down, a drybag makes a softer backrest. For another, the 12" thwart of course takes up a foot of available space for camp gear. Third, you have two choices with a thwart backrest: blow it up firm to get the very back support you're trying to achieve, or leave it soft. If it's blown up hard, unless the back side of your lifevest is really long, you may find yourself with a knot on your spine by the second day of paddling. And of course if if is soft, you may as well stick with whatever your i.k. came with in the first place. The best use for the inflatable thwarts is for day trips where you will encounter stronger hydraulics. These have a ten year warranty.
Please note that AIRE also makes a 7" diameter Thwart for kayaks that runs the same price as this one. As a backrest the 7" size is not very comfortable, so please be aware of this.