Ivory Antique Polymer Grips. Fits the Colt 1851 Old Uberti, 1851 New Uberti, Pietta and San Marcos models, and 1872 Navy. The best way to get the proper fit is for the customer to trace the back strap and fax or mail it to us. These grips will require fitting. Gunsmith installation recommended. Tools needed for installation: 1/8 inch drill bit, 1/4 inch drill bit, sandpaper, glue, file, steel wool, or polishing cloth.