Knobs of this design were made in wrought bronze, wrought steel with bronze coating and cast bronze with 2 1/2 and 2 1/4 inch diameter.  The wrought bronze first appeared in the 1898 supplement to the 1895 Corbin catalog. The wrought steel was listed in the 1900 supplement.  The wrought knobs were listed in the 1905 and 1911 Corbin catalog.