W&P 545 BEAM COMPASS13" + 7" EXTENSION The Beam Compass is used for drawing large arcs and circles on big charts. It is made of high quality aluminum alloy and is precision crafted with a 20 inch (508 mm) overall radius when the 13 inch (330 mm) main beam is joined with the 7 inch (178 mm) extension bar. The beam compass is provided with a 7 inch extension bar, a point, stylus, spare leads and velvet lined, impact resistant case. Made in Germany.