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Tech & Gadgets
Klein Tools MM400 Multimeter — the meter for the engineer who troubleshoots
Klein Tools MM400 Auto-Ranging Digital Multimeter (600V)
Reviewed by the WhyToBuyThis team · Updated September 2026 · How we choose
Perfect for
- Electrical engineers
- Controls and facilities
- Home troubleshooting
- Drop-rated
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- Great gift ideaChosen for real-world gifting
- Hand-pickedCurated, not scraped
- Honest reviewThe catch, not just the hype
Why this gift works
The Klein Tools MM400 Multimeter is auto-ranging and CAT III 600V rated. It measures AC/DC voltage to 600V and current to 10A, resistance to 40 MOhm, capacitance to 200 uF, frequency, duty cycle and temperature from 0 to 1000 F with the included thermocouple, and tests diodes and continuity. It has a 4000-count display, withstands a 1 m drop, runs on 2 AAA batteries and comes with test leads, per Klein.
Electrical, controls and facilities engineers use one daily, and any engineer who fixes things at home will find a good meter indispensable.
Who is this gift for?
Great for
- Electrical and controls engineers
- Facilities work
- Home and garage troubleshooting
Think twice if
- They need CAT IV or True RMS
- They own a good meter
The catch
It is CAT III 600V, not rated for CAT IV service-entrance work; Klein's spec page does not list True RMS; the 4000-count display is coarser than a bench meter; and current tops out at 10A.
Skip if they already carry a Fluke or a True RMS meter they trust.
Key specs
| Voltage / current | 600V AC/DC; 10A AC/DC |
|---|---|
| Resistance | To 40 MOhm |
| Capacitance | To 200 uF |
| Temperature | 0-1000 F with thermocouple |
| Safety | CAT III 600V |
| Durability | 1 m (3.3 ft) drop |
Worth knowing before you buy
- Bundles with outlet testers are separate listings.
- It measures 6 x 3.16 x 1.78 in.
Why we like it
- Auto-ranging
- Measures temperature too
- Drop-resistant
- Recognized tool brand
What to look for in a multimeter
- Safety rating. Match the CAT rating to the work they do.
- Auto-ranging. Saves steps and mistakes.
- Extras. Temperature and capacitance widen what it can test.
Questions people ask
Yes.
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