Thanks for posting this as I've been searching for new locks/clasps to use for my NIC pens. Those look to be an excellent idea - I just wish I could find something similar at Home Depot or Lowes rather than having to order them.
Currently I'm using carabiners (sp), but I've not been happy with them. They were supposed to be making things simpler, but instead I've found that I'm more frustrated than ever! I've also used paper clips, metal ties, and binder clips to no avail. Though I guess it doesn't help the situation that my William has become a master houdini and can escape seemingly with ease...
I'll definitely have to look more into this and see if maybe another store sells something similar if not exactly the same. If all else fails, I now know where I could order them!