Check out this site.
http://www.carcoverworld.com/factoryfivecobra.asp
The link is for their FFR page but I called them and they had a pattern for ERA's. One of the questions they asked me was whether I had a single roll bar or dual roll bars. Maybe they have Backdraft too. Their prices seemed pretty good also. The guy I talked to was Mark. I ordered a "WeatherShield" cover from them to replace the "Superweave" cover I purchased from California Car Covers a few years ago.
The Superweave cover is great. It is water-proof, very light weight, packs down to a very small size and is machine washable.
It, however, also melts when it comes in contact with hot pipes! I got careless with it one day after a cruise and now it bears a resemblence to swiss cheese in certain places.
Hence, I orderd a new one.
It looks like the "WeatherShield" fabric is the same as the "Superweave". I should know in a day or so, as it just shipped from the factory.