Multifunctional Compasses Drawing Tools Spring Chart Planning Line Caliper Spacer Accurate Gauge Leather Tool Feature: 1. Precision mathematical compass - compatible with mathematical geometry and artistic drawing. 2. Unique design prevents skidding while drawing. 3. Precise adjustment - adjusting knobs enables students to produce accurate geometry. 4. You can lock the compass in place and actually hold it as you write. 5. All metal material - made of high quality parts and strong construction, durable enough to last compatible with a long time. 6. Three additional wires can be easily replaced when required. 7. Stability: compass with spring bow and thumb wheel can prevent accidental sliding. 8. Strong metal structure, compact size, light weight, very suitable compatible with senior students and apprentices. 9. Suitable compatible with drawing circle or arc, suitable compatible with mathematics and painting teaching, and also an excellent tool compatible with carpenters. Specification: Material: Metal Dimensions: 10.6 x 2.9 x 0.8 cm / 4.2 x 1.1 x 0.3'' Maximum circle radius: 4.6cm/1.8'' colour: Silver