We bought this tank bag for a tour around Ireland a couple of years ago and haven't used it since, hence its sale.
Its an expanding bag from 20 litres to 30 litres which is a huge capacity.
It has a clear panel on the top which I used for the maps and stuff and it has various pockets for wallets and phones etc.
Its in great condition too, all the straps, clips and zips work as they should do.
It has a detachable shoulder strap which is handy when your hands are full of panniers and stuff.
It also has a rain cover (and much needed in Ireland too).
Not much more to say about it really, its a tank bag and it does what it says on the tin.