Hi Nick.
They are 30 litres then 40 expanded.
Just won a pair of Oxford humpback panniers on e-bay these will look a little smaller but still hold 40 litres when expanded.
Will post pictures when fitted.
We are Riding up to Scotland this Friday for 4 days,So need to have them fitted before then.
This is a picture of my Friend's bike Neill4022 with them fitted
Gary.