The old iron beds often had brass bed knobs that threaded,onto the four bed posts. Also, often times, the two,knobs on the head posts were larger than the two on the foot,posts., ,These two head-posts knobs are the most unusual we have,ever seen. Instead of being round, they are more of a toadstool,shape! They measure 3″ across and stand only 1 1/2″ high.,They have 3/8″ threads. (check your bed posts with a 3/8″,coarse-thread nut.) , ,We have not cleaned these knobs. One could use brass,polish and really make these shine, if desired. They are in,very good shape. There are only a couple of small dimples,which are not distracting. These are old.