Clamp current meter is a current transformer and ammeter in one instrument, is an important branch of the digital multimeter, its working principle and current transformer current measurement is the same. The core of the current transformer can be opened when the wrench is pinched; the wire through which the current is measured can pass through the open gap of the core without cutting, and the core is closed when the wrench is released. Through the core of the measured circuit wire becomes the primary coil of the current transformer, which passes through the current will be induced in the secondary coil current. Intelligent anti-burning and automatic overload protection, any current range will be stably protected, safe and practical. Accurate measurement of Non-contact voltage test, AC and DC voltage, current, capacitance, diode, transistor, resistance, temperature, frequency, etc. It is constructed of ABS material. The length of this product is 15cm, the width is 6cm and the height is 2.8cm. The clamp-on ammeter is referred to as the clamp-on meter. Its working part is mainly composed of an electromagnetic current meter and through the heart of the current transformer. Through the heart of the current transformer core made of active openings, and into the clamp, so the name of the clamp-on current meter. It is a portable instrument that can directly measure the circuit AC current without disconnecting the circuit, which is very convenient to use in diagnosing automobile, industrial and household appliances, and electrical maintenance, and is quite widely used. Item Name: Clamp Multimeter Material: ABS Model: MT87 DC Voltage: 600V AC Voltage: 450V AC Current: 20-400A Resistance: 200K Battery: 2 x AAA Batteries (Not Included) Jaw Diameter: 21.3mm Tester Weight: About 200g Screen: 3 1/2 LCD Screen Maximum Reading: 1999 Standard Accessories: Test Pen, User Manual, Warranty Card Features: Overload Protection, Low Battery Indicator Function, Data Retention Size Details: Tester, LxHxW: 15cm x 6cm x 2.8cm(Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Digital Multimeter 1 x Test Pen 1 x User Manual