Square Ring Mandrel - Steel Smooth - Jewelry Making - SFC Tools - 43-079 Used for custom forming ring shanks and stone mounting bezels. Ideal for use in PMC, hammering and sizing rings for jewelry. It can also be used to form bezels, make chain links and shape decorative pieces. Dimensions: Overall Length: 12, Working Length: 8.5". Smallest Square: 8mm x 8mm (1/4" x 1/4"), Largest Square: 17mm x 17mm (3/4" x 3/4").