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From Pathfinder Guns & Gears, which isn't enabled.

Silencer

ITEM 0
Price 1 sp
Usage held in 1 hand
Bulk L

One of the more prolifically used devices developed in the infamous Alkenstar Gunworks, these small firearm components are capable of muffling most of the weapons' explosive sound when fired. Without a silencer, a firearm's shot makes a loud and distinctive bang, which can easily be heard through doors and thin walls, but firearms equipped with silencers only make a quiet noise when fired. Due to engineering constraints, a silencer can't be attached to any firearm with the scatter trait. Attaching a silencer to a firearm takes 1 minute, and the silencer is consumed the first time a shot is fired through it.

Pathfinder Guns & GearsORC