Model geometry activities for the whole class using our new demonstration compass as students follow along at their desks with Bullseye Compasses (45701). Draw circles 2" - 32" in diameter, construct and measure angles with built - in protractor, and measure length in customary or metric scales with ruler edges. Suction cup fits securely on board for accurate measurements and construction. Translucent plastic improves accuracy by allowing you to see lines, angles and shapes as you draw them. Made of shatter - resistant SAFE - T Plastic. Measures 19.75"L x 4.25"W.