Silver Front Old Belt Buckle Initial M

The belt buckle is from the early 1900's.  It is marked Silver Front Giant Grip Pat. 12-13-21- .  It is tarnished and needs a polish.  It has an intial M on the front.  The front of the buckle measures 1 1/2" x 1 3/8" and the bar measures 7/8" for the belt.