

⚡ Power up your precision with Klein’s MM420 — the pro’s must-have multimeter!
The Klein Tools MM420 is a professional-grade auto-ranging TRMS digital multimeter designed for electricians and serious DIYers. It measures up to 600V AC/DC voltage, 10A current, and 50MΩ resistance, plus temperature, capacitance, frequency, and continuity. Built tough to withstand 6.6-foot drops, it features lead-alert LEDs for safety, a backlit LCD for low-light visibility, and convenient hands-free options like a magnetic hanger. This all-in-one tool combines durability, accuracy, and versatility to keep you ahead on any electrical project.












| ASIN | B0B57PFFYX |
| Batteries | 2 AAA batteries required. (included) |
| Batteries Included? | Yes |
| Batteries Required? | Yes |
| Battery Cell Type | Alkaline |
| Best Sellers Rank | #3,691 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #6 in Multi Testers |
| Brand | KLEIN TOOLS |
| Color | Orange/Black |
| Customer Reviews | 4.7 4.7 out of 5 stars (553) |
| Date First Available | June 27, 2022 |
| Display Style | LCD |
| Finish | Brushed |
| Global Trade Identification Number | 00092644693748 |
| Included Components | Digital Multimeter, TRMS Auto-Ranging, 600V, Temp |
| Is Discontinued By Manufacturer | No |
| Item Package Quantity | 1 |
| Item Weight | 1.76 ounces |
| Item dimensions L x W x H | 9.33 x 5.08 x 3.82 inches |
| Item model number | MM420 |
| Manufacturer | Klein Tools |
| Material | Blend |
| Measurement Accuracy | 600V AC/DC |
| Measurement Type | Multimeter |
| Min. Operating Voltage | 9 Volts |
| Part Number | MM420 |
| Pattern | Multimeter |
| Power Source | Battery Powered |
| Product Dimensions | 9.33 x 5.08 x 3.82 inches |
| Shape | Rectangular |
| Size | One Size |
| Specification Met | Cat Iii 600v Safety Rating |
| Style | Auto-Ranging |
| UPC | 092644693748 |
| Upper Temperature Rating | 60 Degrees Celsius |
Z**H
Fantastic Multimeter
I’ve been using the Klein Tools MM420 Digital Multimeter for a bit now, and I’m honestly impressed with how solid and reliable it is. First thing I noticed is the build quality. Like most Klein Tools products, it feels durable and well-made, not like one of those cheap meters that feels like it’ll fall apart if you look at it wrong. The buttons and dial have a good, firm feel, and everything is clearly labeled. The auto-ranging feature is a huge plus. It makes taking measurements quick and simple without having to constantly adjust settings. The readings are fast and consistent, and the True RMS capability gives me confidence that I’m getting accurate results, especially when working with AC circuits. I’ve used it for checking voltage, current, and resistance, and it handles everything without any issues. The display is easy to read, even in less-than-ideal lighting, and the overall layout is intuitive. For the price, this is a great value. It’s reliable, easy to use, and built to last. Whether you’re doing basic troubleshooting or more involved electrical work, this meter gets the job done without any hassle. Definitely one of those tools you buy once and don’t have to think about replacing anytime soon.
A**N
Solid
Top quality tool to help with electrical repairs. Used it to repair my EGO mower and now use it for other repairs around the house. Came with a case which is a great touch. Display is crisp and its easy to toss into tool box or console of truck.
B**S
Very nice DMM for the money! Easy to use and has a wide range of functions!
This is a very nice DMM! Easy to use and has a wide range of functions. Great value for the money spent! Love it!
S**O
Terrific multimeter, with excellent display
A friend gave me his Klein MM 1000. He is an electrician. It was pretty beat up and have been used for many years in a tough environment. I was really impressed with the capabilities of it. However the switch eventually gave up. I wanted to find something similar and was pleased to find the client MM 420. It can "only" deal with up to 600 V circuits, which is not going to be a problem for me. It measures all the important electrical requirements and also includes temperature with an included thermocouple. I bought this one because the display looked really nice, and it is. They changed the LCD color and it really stands out, especially when backlit. Klein multimeter are "bench tested." I put this in quotes because this particular bench test means that they can handle a 3 foot drop off of a bench. I have been happy with every Klein tool I've ever bought. They offer excellent quality at very competitive prices. You can buy very basic all the way up to professional. The fact that my friend, who has been a career electrician, uses Klein multimeter was certainly a plus to me. Very happy with this purchase.
M**U
Good multimeter!
Used it to check batteries and main (120V) voltage. Auto ranging works well. Used in conjunction with a Fluke 1 AC II for voltage/live detection.
S**N
Pretty good meter
I’ve had the same meter for years and it’s bulky and large but this one is slim and easy to use and store. I bought this one because of the auto ranging feature. It makes it easy to get a quick measurement and if you want a more accurate one, you just hit the range push button to put it into the correct range. It seems relatively accurate on most settings but on capacitors it seems a little off but my old meter was never that great either. Usually if it’s a cap issue it’s open or shorted and rarely just off. I tried out the current (ma) setting and it seems relatively accurate but I set up a specific circuit to make sure it was close but it was out by at least 5%. That based at least on what the resistance was supposed to be and what the meter measured the resistor at. The diode tester works well. My only desire was that it had the bigger screen but that next up model with the larger screen has bad reviews and I didn’t want to hassle with a return or breakage. The kickstand is nice and every meter should have one. I also bought the magnetic holder for it and it’s a great addition. You can just push it flat against a metal surface or use the strap to attach it to something metal. I did get additional leads for it only because I’m picky about what I use it for. I like to be able to use it hands free and I like silicone flexible leads. The ones that come with most meters are usually vinyl and pretty hard but I have to say the leads that came with it were pretty flexible. But were only points to touch with and not helpful for what I do. I think this will be a good meter over the long run. The one thing I didn’t test was the frequency and will have to set up a circuit to test that function. I have a frequency counter so it’s not really a setting I would use. I gave it a 4 because it’s a little slow to settle down and the inaccuracy in the cap and ma readings.
E**Y
Klein Tools MM420 Digital Multimeter, Auto-Ranging TRMS Multimeter, 600V AC/DC Voltage
Klein multi meter works great for my application. I am a diy with some properties and have a basic understanding of AC and electrical knowledge. I upgraded from an old tiny meter that served its purpose but this one is a game changer. You can do pretty much all except for a clamp meter. Love the fact it has LED backlight which its great for dark areas. I added the magnet to the back clip and love its (sold separately) I also use it to check capacitors for the air conditions and works perfect. When using auto sensing you do have to wait about a second or two for it to display the numbers but well worth it.
V**P
Good overall multimeter
I have only used Voltage and Resistance so far and those are accurate. I also really like the probe holders on the back of the meter. Seems to be good quality and easy to read. The only thing I would like to see is bigger diameter probe tips. The included probe tips are too thin and slippery. I had to rough them up a bit with some 400 grit sand paper. Otherwise they were hard to keep in place and get a reading. The meter itself is great, they just need to work on their probes.
D**J
Rewelacyjny multimetr,polecam również dla początkujących.
C**N
Buen producto y fácil de usar.
C**N
Comme sur l’annonce, perfect
A**X
This Klein Tools multimeter is a great choice for electricians, delivering accurate TRMS measurements for voltage, current, and resistance up to 600V and 10A. The auto-ranging feature makes it easy to use, and the backlit display shines in low-light conditions. Its slim, durable design handles drops well, and the included leads are functional for most tasks. Highly recommend for professionals needing a dependable, straightforward multimeter.
G**D
It’s professional grade quality, accurate and reliable. What you’d expect.
Trustpilot
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