90CV Electron tube, photocell, miniature, 7-pin; 
<p>Cathode: Caesium on oxidized silver;
Projected sensitive area 2.4cm2.
</p>
Manufacturer: Valvo, 1950s.
<a href="//commons.wikimedia.org/wiki/User:Mister_rf" title="User:Mister rf">Mister rf</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>