Save money buy (lightly) used! Very good functional used condition, *heavy duty* but portable. Aire, well known quality brand. Heavy duty back support for class- whatever -kayaks, both hardshell & inflatable. 12” diameter. Wedge in place and it stays put. Firm heavy duty seat OR backrest.

Great unbeatable comfort for multiple seating positions - for canoes. extra large/tall seat for taller folks!

lots of tie down points - flexible positioning. and large carry shoulder strap,

raft, kayak (on top stock seat works too)-or as backrest , pontoon, whitewater boat

Additional photos could be provided for serious buyer, if it helps

Good luck with your search