I used to have a plyo box, but at even its smallest side, 18", I would just hit my head on the ceiling when I stood on it. That was a buying mistake.
Now I have this step, it works fine for my needs. It adjusts low, and my knees are dust so I'm never doing heavy plyometrics. They say not to put more than three risers per side under the box. I use 4 per side regularly and it feels stable enough (and is probably 16"), but I probably just voided a warranty or something by admitting that. Bear in mind that this is always going to be a lot shorter than a plyo box, especially if you follow safety instructions.
I use them for a handful of things: Elevated pushups, step up and down, primarily. They get the job done. Also my three year old does "leg day" with me, which entails jumping off this step over and over again.
Would i step on them carrying something really heavy, or go slamming onto them with my full weight? Absolutely not, but I still get some use from them.
Performance
Value
Build Quality