Phosphate binding requires chemical binding, so if they're claiming it's removing phosphate, there is some kind of binder in there. However, the product description is extremely vague, as is the packaging. The beneficial bacteria will deal with Ammonia and it seems like that's how they're advertising this - traps food, waste, etc..
These don't seem like a great item, especially for the price. Pick yourself up some Purigen and some filter floss, call it a day.