Mesh net teether (6 month old)

Traci

What kind of foods can I put in my 6 month old babys mesh net teether thing I'm not sure if it's a teether or what. But its mesh net and snaps together and has a part where he can hold it at the end. What can I put in it for him to chew on ? Besides really cold stuff like pop cycles, would fruit cause him to have acid reflux? Not sure what he could have.