Klein Tools MM400 Multimeter, Digital Auto Ranging, AC/DC Voltage, Current, Capacitance, Frequency, Duty-Cycle, Diode, Continuity, Temp 600V

Klein Tools has always set the standard for professional-grade tools, and this multimeter is no exception. From the moment you pick it up, the build quality speaks volumes — rugged, solid, and clearly designed for real-world job site demands.Accuracy is spot on, whether you're measuring voltage, current, resistance, or continuity. The readings are consistent and fast, with virtually no lag, which makes troubleshooting efficient and reliable. The auto-ranging feature works flawlessly and saves time in the field.Durability is another standout. This meter is clearly built to last, with a reinforced casing that can handle drops and daily wear. The display is sharp and easy to read, even in dim lighting, and the controls are intuitively laid out for one-handed use.Packed with features like true RMS, backlit display, and a wide measurement range, it’s everything a professional or serious DIYer needs — without the unnecessary fluff. Klein Tools continues to prove they understand what technicians actually use and value.In short, this meter nails it: fast, accurate, durable, and thoughtfully engineered. If you want a meter you can count on day in and day out, this is it.

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.

Measures as accurately as required. Has many features as other similar devices but this device is sturdy and does not feel cheap in hand. It has a good weight not heavy. So far quite reliable. I use it ocassionally without issue. In automotive electrical, computer electronics and home appliance electronics. It performed well across all those areas. Great price.

Not bad. Mid-tier capabilities with a great screen. Thinner than most full functional multimeters, side lead jacks allow for thinness, better portability without sacrificing safety or ability to change leads. As capable as my Fluke 117 but 1/3 the price and easier to pack. I would consider this to be the perfect back up to my Klein 810 Pro or for standalone use in a quick troubleshooting scenario. Nit picks include position of lead jacks right where my fingers hold the meter; lack of non-contact voltage sensing and a lack of a work light. Any two of those three would make it a 5/5.

The media could not be loaded. DIYer ESSENTIAL. There are a LOT of bits and should cover almost all DIYer situations. No issues except the bits come loose from their friction fit slot.PROS✅ Klein = Awesome✅ Comprehensive - AC/DC voltage, AC/DC current, resistance, frequency, temperature✅ Durable - rugged, drop-resistant housing. Meets specific safety standards also.✅ Display - bright backlightCONSNone!TIPS💡 Storage - it’s a piece of sensitive equipment. Store and treat it with care.💡 Multimeters can seem scary to a DIYer - watch some youtube videos!

This is for the 420 with lead alert.It is small and light, yet very sturdy, and has many functions for everyday and occasional use. I bought to use at home. I've used it on my car and in my house for electrical troubleshooting. Would definitely recommend for a home DIY tool. I cannot give a professional opinion on everyday work use.

Replacing my old multimeter I really notice the white on black LCD, it's so much easier to read than my old meter. It is thin and the probes come out the side of the body. Rubber grip is good. I appreciate the zipper pouch. It does start beeping at you before it auto powers off which is a little annoying, I myself don't need a warning it's shutting down. I thought the probe tips were too small but it looks like the sleeves come off when I need that. Overall I would buy it again.

I should know to TRUST KLEIN Tools. Extras others require you to upgrade in price. Nice Quality. Love the Hanging MAGNET Strap.