Thanks for the reply but that's not quite what I'm after, I'm thinking of fully removable ones which are inserted into a permanently mounted receptacle, which is itself concreted into the ground.....but the description "removable post" seems to yield more results than what I was using so ta for that.
I know what you are looking for. Yes they are available . a three foot aluminum pole slotting into the receptor in the ground. I bought mine in Crothers Locksmith in Walkinstown a number of years ago.