The pain inhibitor is a cybernetic implant granted to Conrad Kellogg by The Institute. Though its purpose is never stated in-game, it can be implied by its name that it dulls painful stimuli, allowing Kellogg to fight more effectively without distraction.
It can only be found on Kellogg's corpse in the Fort Hagen Command Center after killing him, and cannot be pickpocketed. Also, unlike the cybernetic implants found in previous games, one cannot have it implanted in themselves and thus its only purpose is to provide story flavor.
The cybernetic pain inhibitor can be sold, or placed as a decoration.
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