Vaude brand bicycle saddle bag
Condition: near new (very, very little use)
Capacity: 7+3 liters (10 liters)
1 large central pocket featuring 2 zippered compartments inside.
Also includes 2 zippered compartments on the sides of the bag.
The bag itself is a 7-liter model; however, with the central zipper covering almost the entire circumference of the bag, it can be extended by 3 liters, bringing its full potential to 10 liters.
Supplied with its waterproof rain cover (orange) as well as the seat post mount (see photos).

Price negotiable within reason....