First off, I'm reviewing the INNOVA 3300. This is a manual-ranging multimeter with detachable probes that uses a 9V battery and does not have a continuity beep. Amazon is now showing pictures of the 3300A under the same product listing from which I originally ordered. The 3300A is an auto-ranging meter whose existence the INNOVA website doesn't even seem to acknowledge. The 3300A has permanently attached probes, a continuity beeper, and apparently uses two little alkaline button cell batteries (which I imagine would need changing more often, but I don't have direct experience with it). The 3300A also eliminates the battery-test modes which allow you to make sure the voltage you read on a battery is a voltage it can actually supply under at least a little bit load, and doesn’t measure current. I don't like it when multiple products are sold under the same Amazon listing like this. It makes it difficult to tell whether the reviews you're reading have any bearing on the product you'll actually receive. And I can offer no insight into which version of the product you'll receive if you place a purchase right now. I have the 3300 manual-ranging meter. I originally bought this multimeter for less than ten dollars in late 2013, for use on a relatively simple low-voltage DC electronics project that I was working on. It served me fine for that purpose. My only real complaint was that upon opening it up I found that one of the wires leading to the battery had been smashed between the housing and the circuit board when it was originally assembled, damaging the insulation. I put some electrical tape over it, but the meter seemed to be working fine, so I gave it a four-star rating here. In the following years I used it for general purposes that consisted mostly of checking voltages on batteries and power supplies to see if they were working. Occasionally checking for continuity to try to figure out how something works. It mostly performed fine, and the lack of a beep associated with the continuity test was the only feature I particularly found myself missing. Over time, though, the 20V DC range started acting funny, reading as much as 7V when the probes weren't touching anything. This forced me to use the 200V range, which was disappointing and cost me some resolution, although in truth I was never doing anything where a small fraction of a volt would make much difference. When changing the battery didn't fix the problem, I revised my rating from four stars to three. (I will also note that any multimeter should have a fuse inside it--that's another thing to check if it starts acting funny.) Eventually, however, I disassembled the entire unit and found yellow plastic shavings collecting mostly on the front of circuit board at the center of the rotary dial. I assume these shavings, shown in the attached picture, were gradually worn off the casing little by little each time I rotated that dial. Eventually, enough of them must have built up to affect the quality of the electrical contact, because after I cleared out those shavings my 20 V DC range was working properly again. This doesn't exactly speak highly of INNOVA's build quality, but it was a really cheap meter. (Although the current 3300A is not as cheap as the 3300 was.) I tested it against a Fluke 117 that I recently bought, and got similar readings from an old 9V battery that I had lying around (Also shown in an attached picture). So my INNOVA appears to be back in fighting shape for now. This leaves me with a bit of a conundrum. Is it a four-star meter again, given that the problem was fixable? Or is it a three-star meter because of the poor material quality that allowed this problem to occur in the first place? I'd probably give my 3300 it 3.5 stars if I could. But because you don't know if you'll receive a 3300 or 3300A, and because the 3300A strikes me as being a little bit cheaper in construction from what I've seen in an online disassembly video, I've decided to stick with three stars. When it was half the price of the 3320, it perhaps merited consideration for extremely low budget projects. But given current prices, you're probably better off paying five dollars more for the 3320. Now, any discussion of multimeters probably merits a little context. This is a cheap meter that's fine for doing low-consequence, low-voltage DC electronics work, but is probably not the safest thing to be using if you're operating on 120V or higher mains electrical items. I'll admit, back when this was the only meter I had, I used it a couple times to check a 120V outlet without any mishaps, but these cheap meters just don't have the input protection of more expensive meters in case something goes wrong. And some fairly dangerous things can happen in the event of operator error and/or unexpected surges. You'll see twenty-dollar meters with four-star ratings, and you'll see two-hundred-dollar meters with four-star ratings. The people rating those products are using them for different purposes. Please make sure that the tool you're using is appropriate to the job you're doing. The "Cat" rating will give you some indication of how much abuse a meter can take, but some shady manufacturers have been known to exaggerate their ratings, so use some common sense. And if you do need to poke around in the vicinity of mains electricity then (1) this meter is not the right one for the job, and (2) get yourself a non-contact voltage detector so you're not guessing as to whether a wire is live or not.
