replying to fred, 3axis wrote: I tried the dimensions you mention, 3/32 is too small, BS111 is 10.77mm ID x
2.62mm cross section. I have ordered some from ebay and some 11mm x 2.5mm, I will try to remember to report back which fits best but measurements I did of a hozelock copy was 11mm x 2.55mm so it should be the BS111. I contacted sealsuppliesuk who is an ebay seller and they were extremely helpful and I bought one listing of 10 nitrile o-rings in one size and they said the would send me 5 of each size to try them, they also offered to determine the correct size if I posted the hozelock one to them.