Product details:
Designed to work with the Robert Sorby Patriot Chuck, 4-1/4 Jaws enable the chuck to hold a much bigger recess or spigot, making it excellent for turning bowls and platters over 16" across. EnglandSpecifications for the 4-1/4" Jaws- Minimum External: 4-1/4" (108mm)- Maximum External: 5-1/4" (133mm)- Minimum Internal: 3-13/16" (97mm)- Maximum Internal: 4-13/16" (122mm),Hardware > Tools,Robert Sorby
