Hi John
I have a black Bagster tank bag - the model is Minea- which I used on my FJR but I don't use it on my ST. I'd be happy to sell it as it is just sitting around. I purchased it new in 2009 and used it during 2009 and 2010 and it is in good shape. It has a clear plastic waterproof cover which fits over it as well. Like most of the bagster range it has back straps which fold into a pocket beneath the bag when it is clipped onto the tank cover, so you can carry it around as a backpack as necessary.
If you look on the bagster website, you can see the measurements. They can be unzipped to expand upwards to fit more stuff in.
If you are interested, let me know on chrisdaly45@gmail.com
Cheers
Chris