The units also conform fully to IEC 61010-1 for use in Category III 600V applications, and provide all of the facilities needed to meet insulation testing requirements relating to the current edition of the IEE Wiring Regulations. In line with other products in Megger's comprehensive new contractor range, MIT300 insulation testers feature rugged construction, with an impact-resistant rubber-overmoulded case, and innovative circuitry which guarantees high accuracy combined with stability of calibration. All instruments in the new range provide indication of insulation resistance up to 999Mohms, 200mA continuity testing, a fast-reacting continuity buzzer, and facilities for nulling the resistance of the test leads. The entry-level MIT300 offers insulation test voltages of 250V and 500V, while the remaining models allow testing at 250V, 500V and 1,000V.In addition to the basic features, the mid-range MIT310 adds a default voltmeter function, while the MIT320 supplements these facilities with an a backlit display, illuminated range panel, insulation limit alarm, resistance measurement, and an adjustable threshold for the continuity buzzer. The MIT320 is also supplied with a switched test probe to speed hands free testing. An illuminated switched test probe is available as an optional extra for use with the MIT320. The MIT310, and MIT320 testers incorporate dual solid-state displays which simultaneously show the test results numerically, and in the form of a moving-arc bar graph that accurately simulates the operation of an analogue meter. All testers come complete with a full calibration certificate. For users who prefer a true analogue device, however, Megger is offering the MIT310A which has features similar to those of the MIT310, but with a conventional moving-coil meter movement in place of the digital display.