Easy-to-use one key operation Efficiently identifies the traffic direction and frequency tone (270Hz, 1KHz, 2KHz) with an audible warning. The display shows you the relative core power clearly Includes 3 mm, 2 mm, 900 nm (0.90 mm) and 250 nm (0.25 mm) adapters for different sized fiber optic cables Included sunshade protects the fiber optic cable from interference to provide more accurate readings Durable metal housing provides long life and durability LED indicator lets you know when the battery is running low