Anyone know what this is? Looks like a mold pin clamp but

[woodchucker]

It doesn't come apart... And I don't think a tool is available to grab the drum.
Cleco something??? The stamped cover on the drum says LOCK SEAL

 

[Nutfarmer]

Looks a lot like what I used to use to shut off water sevices. The two pieces will snap together locking. There should be a about 1/8 inch hole in the cap that a special tool will unlock the cap off the stud. This would fit in a corporation stop valve that had ears on the valve stem and body that had a hole in them that the lock would fit ,this prohibiting the valve from being opened

 

[woodchucker]

That would make sense. No hole though.

 

[francist]

Something like this maybe?…

 

[Nutfarmer]

Under the seal cap would be where a hole or lock would be