These bear the ACF online poker site logo.
They were available in very small numbers as samsalem stated as prize to winners in large ACF tournanment and online tournament.
I am pretty sure they were never played in an official game in the ACF and were designed to be used in home games.
They are plastic based (probably china made) chips. Not low quality, but not anything fancy either.
I have a set of these. I was planning on keeping them due to rarity, but would consider parting with them.
If you have a sample, I recommend keeping them, as they might become collector items.
There value is probably around what china clay exchanges for. It can be argued if ACF collectors would pay a little more to acquire them, but I would not bet my life on this.