BOYS ARE THE BEST! But then again, I'm biased.
I purchased some great belly bands right here on YT. Remember though, only use them as a training tool instead of a solution to the problem.
Here's her website:
Litlbit Wraps / Puppy Wraps
I love these because of the velcro/snap button option. All other belly bands Kaji managed to take them off, he couldn't with these!