Precision metal compass with spring-bow head and center wheel, hinged leg joint and needle holder in needle leg. Includes extension bar and universal adapter for writing instruments. Maximum circle drawn: 10-3/8" (265mm), with extension bar: 19-5/8" (500mm). Overall compass length: 6-1.8" (155mm). Spare parts box includes two pieces of lead and one needle joint. Comes in plastic wallet. Size: 4" x 7/8" x 8-1/8".