This is the big white cooler box that I think came as standard with the 26X to fit in the starboard underseat storage space (or maybe it was a boatshow extra).
Anyway it is unused and available for sale at £30
It's labelled "60" - which I guess is quarts as it is US origin
External dimensions are 55cm x 40cm x 42cm high including carry handles
Collect at Windermere? Or discuss delivery.