The Fluke 771 is a high-precision milliamp clamp meter engineered exclusively for industrial 4–20 mA process control loops. Based on non-intrusive inductive measurement principle, it reads DC mA signals from transmitters without wire disconnection or equipment shutdown, eliminating downtime losses and wiring teardown labor. Featuring ultra-fine 0.01 mA resolution and industry-leading 0.2% accuracy, it precisely identifies transmitter zero drift and faint ground interference. The detachable extended clamp head with built-in spotlight enables easy inspection of wiring inside cramped, dark control cabinets. Dual ranges cover standard 4–20 mA loops and legacy 10–50 mA industrial equipment, while the dual display simultaneously shows mA value and percentage span, allowing technicians to judge loop status without manual conversion. IP40 dustproof lightweight 260 g construction and long-life alkaline batteries make it a dedicated portable tool for loop troubleshooting and on-site calibration in automation, chemical and power industries.