It is a transducer which allows your multimeter to measure current data and enable your oscilloscope to measure the current waveforms. Its current transducer is composed by permalloy and hall element, which linearly transform the AC or DC current to AC or DC current voltage. And if connect to an oscilloscope by BNC type connector, you're able to observe the current waveforms; If connect to a multimeter by banana type connector, you can obtain the current data. General Specifications: Captured Conductor diameter Size: 30mm maximum Low Battery Indicator: Red LED lighting Operating Temperature: 0? to 50?, 70% R.H. Storage Temperature: -20?~+70?, 80% R.H. Battery type: 9V DC, NEDA 1604, 6F22, 006P Battery Life: 100 hours typical with carbon-zinc Weight: 250 gram typical Dimensions: 195 mm (H) x 70 mm (W) x 33 mm (D) Output: wire with a straight banana plug or BNC connector Efficient Measure Range: 1mV/100mA: 100mA to 20A, multimeter range is set to DC or rms AC 200mV 1mV/1A: 1A to 200 A, multimeter range is set to DC or rms AC 200mV 200A to 650 A, multimeter range is set to DC or rms AC 2V Accuracy: DC current: 0 to 650 A, ±(3% + 2 A of numerical reading) AC current (50Hz to 400Hz):0 to 500A, ± (3% of reading + 2A);500A to 600A, ± (6% of reading + 2A);600A to 650A, ± (8% of reading + 2A) Load Impedance: 10K? (typ) Package Includes: 1x CC-650 Clamp meter 1x Manual