Klein Tools MM325 multimeter

Under IEC 61010, the category reflects location and transient risk: CAT II for plug-in equipment, CAT III for building wiring and panels, CAT IV for the service entrance and utility supply. The voltage is the working voltage at that category. The lowest-rated part (meter, leads or probe) sets the limit.

This is the highest DC voltage the meter can display, relevant to batteries, controls, solar arrays and automotive work. Solar strings can run well above residential voltages, so check the range covers your systems. As with AC, the range is separate from the CAT safety rating.

This is the highest AC voltage the meter can display. It should comfortably exceed what you test, such as 120/240 V US residential or 277/480 V commercial. The measurement range is not the safety rating; check the CAT rating for where the meter may be used.

This is the highest DC current the meter can read. Many clamp meters measure AC only, so a DC figure matters for solar, battery, automotive and DC motor work. On multimeters, DC current is usually measured in series through a fused input. A blank entry may mean no DC current function.

Display counts set how many digits the meter can show. A 6,000-count meter reads up to 5999 before changing range, so it shows 240.0 V, while a 2,000-count meter would show 240 V. More counts means finer resolution, not necessarily better accuracy, which is a separate spec.

This is the highest resistance the meter can read, in ohms, kilohms or megohms, covering continuity, heater elements, motor windings and sensors. Always measure resistance with the circuit de-energized. This range is not an insulation test; that needs a dedicated insulation tester (megohmmeter).

This lists the cells the meter or tester runs on, such as AA, AAA or 9 V. Common sizes are easy to find on the job. A low battery can cause inaccurate readings on some meters, so replace cells when the low-battery indicator shows.