Hey Plyerman what are these?

[skipskip]

says "Aircraft Tools Inc"

a cup on one side, C on the other.

for squeezing lead seals?

DSCF4635 by Skip Albright, on Flickr

[moparthug]

I believe they are used for setting temporary rivets while setting up the aircraft panels, I stumbled across a couple of these with a dozen or so big spring loaded expanding fingers.

[moparthug]

It looks close to the ones I have.

[bill300d]

They do resemble Cleco pliers.

[lptools]

Hello, Skip. I believe the trades guys refer to all of the clamps moparthug is showing as "Clecos", regardless of the manufacturer. Like calling all arc joint pliers Channellocks. That being said, yours would be most likely be called Cleco Pliers. Regards, Lou

[Plyerman]

I knew they were called "Cleco" pliers, but I never bothered to learn what clecos were or how they were used. Until now. Skip to about 1:20 on this video and you can see the fellow using the pliers and the fastener:

https://www.youtube.com/watch?v=gdHEL0BVvtY

[turnnut]

  and now we know,  learned something new today,  thanks plyerman.