[Hallicrafters] Tube Shields.

[Tom - Vintage Radio]

If anybody out there, has the IEC tube-shields as used in R-390s and many
Heathkit stereo amplifiers, I need some... they are the BEST... about 48%
less retained heat, than the bayonet or slide-down type.  Some of the best
"home brew" ones I made, were constructed of copper-screen wire, with edges
soldered together... they shield WONDERFULLY, and do NOT retain heat.

ELECTRIC RADIO magazine had an article on them... seems like last month.

Tom - WØEAJ