Staedtler 660 Mars College Drawing Board Drafting Head | For use with the Staedtler 661 A3 drawing board and Staedtler 661 A4 drawing board | Single-handed use | Stop/Go push-button for easy setting at desired angle and freewheeling | Two transparent rulers with double sided, opposite-running scales | Parallel guide lines serve as hatching aid | Opposite-running protractor scales from 0 - 90 with additional marks at 7 and 42 for dimetric projection | Automatic settings at 1 interval | Uninterrupted drawing of right angles possible | This item is manufactured in Germany