Living World Cuttlebone Bird Treat
these came bigger than i expected them to, having only found smaller ones in my local pet shop, these fit perfectly inside the JW cuttlebone holder, though it took some prying to get the little metal holder pried out of the bone.
These cuttlebones were so small I had a hard time hanging them in my bird's cage. There was not enough Cuttlebone to put in metal hangers. In cage for 1 day before bird used them up. Waste of money.
These are not very hard evidently. My birds chewed through it like a piece of bread. I have to find a different brand elsewhere.