This device was originally conceived as a 40- channel wireless radio detonator with a cable connected trigger-switch unit.  The episode Director requested that the coiled cable joining the two devices be removed-- suggesting that they too operated through a radio connection​.
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To expedite this assignment (and save money) the ARROW Prop Department suggested that the LED indicator panel from a previous ARROW build be utilized....  namely, one of the two such panels used from a so-called prop "RDX bomb" (Depicted below).
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RDX Steel Barrel Bomb & Radio Detonator Device
Adopting components from previously used props made this a very efficient and cost-effective build.