The Sculptors Apprentice, Highest Quality Proportional Divider, Enlarging Caliper Tool for Sculpture Measurement The Highest Quality Proportional Calipers on the Market. Made from stainless steel for durability and rust resistance for sculptors using water-based clay Custom fabricated oversized tightening nut so you can use them with clay covered hands. 9 different enlarging scales: 1:1, 1:1.75, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:5 Quickly, easily and accurately change between scales with no guess work!