British Army Gas mask filters S10 (Catterick Garrison DL9)

For my brother who is fighting in Ukraine. A friend is driving over there from the UK soon so he is going to take over a box of stuff that we're getting together for him. A gas mask & helmet have been kindly donated but we need Avon S10 filters for the gas mask...he has recently recovered in a hospital in Kharkiv after being gassed & the Ukranian army issue gear is very poor quality & provides little protection. Any other army gear or ration packs could be useful too, thankyou 💜