[R-390] Tube shields

[Cecil Acuff]

Hey Folks,

        Found something interesting this evening while working on an R-390 
restoration.  Found two ELCO tube shields...the silver twist lock kind with 
the IERC finger style contacts between the shell and the spring.  I thought 
at first some wise guy had shoved it up in there to make a somewhat hybrid 
IERC tube shield.  Upon closer investigation it appears to be factory. 
There are two folded indentations in the shell that catch the bottom of the 
finger contact piece to keep it from sliding out when the shield is pulled 
off the tube.

Interesting....

Is this a new find or are these shields pretty common?  First I have seen! 
Not sure they are any better than the silver variety as far as dissipation.

Cecil....