I have a lightly used Medium (13" tall) Active Contour ADI Carbon Fiber Backrest for sale. The shell is 15" wide, and the upholstery adds another 3/4".
It comes with brand new 2-Point Pro mounting hardware. It was mounted on a 15" wide chair, but would easily fit 16" as well.

I used it for about one month before switching to the Low 10" model. There is some light scuffing on the shell, as well as some wear on the front of the upholstery where the velcro of the seat pan was grabbing at it when the back was folded down.

This item is going for $609 on Sportaid. I would like to get $300 + shipping.

I couldn't get the stupid images to load, so here's an Imgur gallery: http://imgur.com/a/RAL80

Thanks,
Taziar