Antique cast iron branding iron letters are H F sale

antique cast iron branding iron has two letters that are H L the sale letters are small they measure 5/8" high and 3/8" wide. i have no ideal what it was used on.It measures 23" long overall the head measures 1-3/4" x 1-3/8" overall, The round handle measures 3" x 3" it is very old and solid iron with heavy pitting but still very solid.