This is a nice basic tank bag from East Germany, branded "B-Squared".
It's got a nice two piece design, which means you can just carry the map, or a lot more.
Extra pockets, shoulder straps, and expandability means you can carry even more! It's got all the features of a regular, $100+ tank bag and has served me well for a couple of years.
Pick up this handy tank bag for just $25!!!