The CST/Berger K & E Type Topographic Abney Level model 17-643 is 6-3/8" long and extends to 7-3/8" long. It's equipped with two interchangeable arcs with 47mm (1.85") radius: one arc graduated in degrees, 0 to 60 Degrees in both directions, and the other arc graduated in topographic scale. The index has friction movement for time adjustment. Comes complete with a cordura belt loop case. Includes a 90 day manufacturers limited warranty.