SHELTER YOUR EYES FROM THE GLARE - CUT OUR HARMFUL EMANATION FROM YOUR VALVES 1923 STYLE

I have previously joked in this blog about the use of condoms to 'improve the sound' of valves, little knowing that in actuality, in 1923, the Thermic Valve Cap  was a reality and they probably even sold a few as well.  

Wonder what alternative uses you could put them to?    Not much use to me though as in 1923 these must have been sized  for the average Mullard PM B4 based valve whereas I am more a KT66 man and these didn't come to market until 1937!!!!!!!!!!!