This is an interesting idea! It’s basically a quick tailor for any pair of jeans! My big booty is always fighting with my smaller-than-my-booty belly when it comes to jeans fitting, and this is a handy little helper in that department! And I like the packaging, too!
I bought something very similar (http://www.instantbuttonforjeans.com/) to these for a pair of jeans that lost a button, and they work great. They’d also be good for adjusting your jeans to be tighter or looser.