[Chilibit]

I tried at least three supports. Most leak air, including the ones from seat manufacturers. This one from Amazon works like a charm and holds air (in my case) forever. And it costs less.

Embrace Air Portable Backrest Inflatable Support Cushion

I failed twice with Corbeau.

I got my seats from JEGS. Nice to deal with. Ask me if you want something measured. I have the 17 inch width.

A word of warning. If you let your car sit out in a rainstorm with no top the seat bottom will be four inches deep in water when you drop in. And it will not be obvious. A garbage bag can be your friend.

I think Ultrashield is very close to the same, but that is not from hands on experience.

Kirkey does great welding on the aluminum. These are in keeping with the spirit of the early days. If you need to mod it, drill it, and press on. Functionality in spades.

Ciao