The Marlin Springbow Compass Set with Leads features a highly durable, nickel-plated solid metal technical drawing instrument. An integrated central thumb-wheel micro-adjustment spindle controls leg widths with absolute precision. The sturdy spring-bow tension mechanism eliminates leg flexing under heavy manual downward force. A sharp steel anchoring needle point stops slipping on technical drawing paper. It serves as an essential scholastic math tool for drafting flawless arcs. This two-piece layout includes a protective storage container and spare leads.