what size pack cover

[spiritwalker]

Hi all,

i am after a waterproof pack cover for the german army mountain rucksack
http://www.military1st.co.uk/products/bags-and-rucksacks-backpacks-and-rucksacks/30323b-old-german-army-military-rucksack-backpack-30l-olive-od.html

does anyone know what size cover will fit over this snuggly please preferably from experience as i want to get the right one from the off

ta

[TFan]

Can I ask a similar question? I'm looking for a pack cover to fit the longback infantry bergen, partly for waterproofing but mainly to look less military. I do feel I sometimes look like an extra in a bad war movie when out and about.