Boingos come in pairs, with hooks at each end, and are used much like pins in that you only hook them at each hip. (gentlediapering.com)
You can also use Boingos which also use teeth to fasten diapers, but each one only has two sets of teeth and you need two of them to fasten a diaper. (gentlediapering.com)
Do not allow your child to play with Boingos, they are not toys. (kellyscloset.com)