My friend, who has two dogs, only asks that I get them rawhide bones if I want to give the dogs gifts. They both like them and my friend says that they are the best for them.
If the kind you give your guys upsets them, you might ask their vet if there is something about some bones that are manufactured differently and might upset your dogs tummies. He might have had some information about them that might give an alert to vets to pass on to their clients.