The Riser-Bond Instruments MODEL 2901B + is a radar type DIGITAL TIME DOMAIN REFLECTOMETER, CABLE FAULT LOCATOR. PHYSICAL DIMENSIONS: Height: 3.25 inches (82.6mm) Width: 6.06 inches (153.9mm) Depth: 6.25 inches (158.8mm) Weight: 3 pounds (1.35kg) POWER: Four cell NiCad battery pack. ENVIRONMENTAL: Operating range -10°C ( + 14°F) to + 55°C (4- 131 °F). Storage range -30°C (-22°F) to + 70°C < + 158°F). DISPLAY: 41/2 digit Liquid Crystal Display with 0.4 inch characters, annunciators to indicate OPEN or SHORTed cable, low battery, powered cable, and readout in meters or feet. DYNAMIC RANGE: Better than 20dBRL in the least sensitive mode to better than 40dBRL in the most sensitive mode.