I've got three types w/ several that read basic measurements and these are handy when you want to be sure what you're using either to double check or verify you have the right one. The smaller pF range types can vary more than you think. A second one is an ESR-type tester just for measuring electrolytics and can also be used in or out of circuit which tests using a high frequency on the cap, and the third is one that checks for passing DC that's a little primitive but hey you can build it yourself for cheap so beggers can't be choosers. :) This puts a DC charge on the cap using a SPDT or DPDT w/ one way being a momentary but you can use a simple SPST on/off/on if you want. Anyway, press to charge the cap and release or switch to get a DC reading w/ your meter (or flip it the other way) middle position is off. This doesn't test w/ high voltage but you're supposed to scale the 9v to get an idea what you've got. It can check all types of caps. With e-lytics you will get some DC and this is what you're suppposed to scale and get the feel for, the smaller ODs, Mallorys, ceramics, etc. shouldn't pass any DC. With practice you can get fairly good w/ it and if you use recycled parts it may be worth it and/or simply fun for a quick project?