Burned out impulse pack (center)

Impulse packs were small devices integral to the function of impulse engines.

In 2265, the USS Enterprise's starboard impulse pack was severely damaged due to an encounter with the galactic barrier. Gary Mitchell, who had gained incredible psychic powers due to his exposure to the barrier, informed Lieutenant Lee Kelso of the damaged points on the pack, and warned him that, if they tried to activate the pack in the state that it was in, they would blow out the entire impulse deck. (TOS: "Where No Man Has Gone Before")

In the first draft of the script, these components were instead described as "mesonic terminator leads" and "terminals". When physically shown, the script notes (first and final draft) described the prop as a "terminator connection".
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