Class B autoclave used for sterilizing all objects (solid instruments, porous objects and A and B hollow objects, both packaged and un-packaged); Class N autoclave used for sterilizing only un-packaged solid instruments; Class S autoclave used for sterilizing un-packaged solid instruments plus one other of the types indicated for cycle B (to be specified by the maker). Class B autoclaves are the autoclaves that can carry out cycle B and thus can sterilize any kind of object.