I purchased the 16" x 18" x 20" titan plyo box and was impressed with the speed of deliver and what appeared to be  a good product, but after multiple attempts to incorporate  the box into my workout I have not yet found it is stable enough.  If using for box jumps on the 16" side if you land exactly in the middle you are fairly safe but forget it on the 18" or 20" side it is wobbly and unsafe.  Even just using for lateral step-ups on the 16" side it is too flexible to be safe/usable.  And no, I'm not too heavy, I am a healthy, fit, 165 lbs.  Save your money.