Frame straps
http://www.ebay.com.au/itm/New-Corner-Clamp-Band-Strap-4-Jaws-For-Picture-Framing-Holder-Woodworking-Drawer-/142075244222?epid=2114663160&hash=item2114582ebe:g:uZ0AAOSwIgNXobfB

I lost one, so I made another one to replace it.