Sometimes sellers selling clothing or footwear (or in my case, slippers) Will say in the description 'other sizes available, contact me for details'
If you do contact the seller and they say they have the size you want, insist you will only bid on it when it is listed with those size details on ebay.
A seller told me he had my size, but to bid on the other size he already had listed. I did, thinking all was well, still paying by pay pal etc etc. But he didnt send me the size he had promised me in the email/ask seller a question correspondence.
I was then stuck and unable to complain via ebay, as he had sent me the item listed, even though it wasnt what he said he would send me.
So be careful and bid smart