Yes, that is the seat.
I ordered mine from outdoorplay.com it was a special order seat and I ended up calling them on the phone to do the order. I live in cowboy (not rafting) country, and that is the reason for mail order.
It may well be out there from outfitters closer to you.
I do not know the answer why, but I did not see this seat offered as an option when I got my Aire Outfitter IK in Salida, CO while boating on the ARK. My guess is the Cheeta is what Aire ships and while that seat works for many, the Cheeta does not work in IK's for me. While the Cheeta is a good seat, no doubt in my mind that my old crazy creek unit would work great in a IK. Maybe a bit of engineering mods on the tie ins. I have used that crazy creek on a canoe and on top of a dry box in my raft. If I am just drifting along in the IK, the Cheeta works ok. When I want to get that locked in forward chest lean that works well for me in a hard shell, the Cheeta style seat does not give me support. Even when I adjust all the straps, it does not work for me.
Based on feedback from one of my IK owner buds in CO, we made a foot brace out of a length of plastic pipe (we used ABS type pipe as it is a bit stronger than standard PVC) plastic pipe and a cam strap thru the pipe to the Aire IK tiedowns. This combo gave me back support and foot brace to lock in the IK similarly to the hard shell altho not as secure as the real hard-shell kayaks this is the best IK option I have found. I am a beat up old Squirt boater and this type brace feels like the heel brace I had in my Big Foot. Bottom line it works for me.