We use both these and the cleco clamps that can also be purchased.
These are temporary rivets... they come in really handy to align pieces while drilling them... and to hold them together while riveting...
As I mentioned they come in two varieties
Hole grip clamps... (the standard cleco..) Just remember to get the correct one for the size of the hole you are drilling!!!
and Edge grip clamps (little edge clamps)
they both are taken on and off by a pair of cleco pliers.
See this reference in McMaster Carr
http://www.mcmaster.com/#cleco-clamps/=crdurk
They have many uses... in the shop and in the pit... for temporarily fastening something...
I would suggest that more teams try them... they come in very handy