The Staedtler MasterBow Comfort Student Compass STD55140WP is an all-metal spring-bow compass designed for precision. It features a center wheel that allows for accurate settings and prevents unintended adjustments, with a maximum circle diameter of 10-3/8'' (265mm). The design includes an interchangeable lead part and a nickel finish to resist rust and stains. This compass comes with a spare lead tube and is packaged in a convenient plastic wallet.