These underwear are PERFECT for any guy that wants to fill out a pair of pants. Perfect for jeans and even slacks. The padding is soft, but firm enough to do the trick. They are, however, cut very small, so if you are, say, a size 33/34W, the XL will just barely be big enough -- and even they will be snug (not tight, but snug).  That's not a huge problem since, as shape-enhancing underwear you don't want them baggy.  But be aware that they are best suited for smaller guys (size 28-32) unless you go for XL.  Anyone over size 34W may find XL uncomfortable.

They are well made, and the padding does what too many other butt-enhancers do not -- these extend the padding down to the top of the thigh so you don't have conspicuous padding at the top of your butt, just below the belt.  That looks weird and is a dead giveaway. These give the appearance of a fully round butt, which is what you'd want.  They are also sturdy enough to be worn with denim jeans.

Two issues though (other than them being cut small): First, the padding could stand to be a bit firmer since anyone that actually feels them will know it's padding. Of course this is only an issue for some, but think about it: if they are doing their job, someone is going to want to feel. So, if these are ever updated, a slightly harder (perhaps non-washable) pad may be good insert.  Second, if you are one that would wear these in an environment where your shirt may be off or your underwear would show, the label band shows "Rounderbum" and a bunch of "o"s.  Anyone who sees that will know you have on shape-enhancers... which defeats the purpose!  A better design would be to keep the label band free of labeling (e.g. just a black band or an inconspicuous row of "o"s), make them low-cut, or put the label down the side so it is not visible if your shirt comes up or off.

Rounderbums next trick should be to make undergarments that can work with or as square-cut swim trunks.