Destroyed Collar

The destroyed collar is a slave collar that has detonated, and can be used as a necklace of sorts that appears that the wearer attempted (and failed) to take it off, judging by the decapitated head and the nearby wrench.

Characteristics
The collar, when worn, has zero DT, and no in-game effect except for being visible as a bulky metallic collar on your character with no visible differences to a functional collar.

Locations
It is obtained when you start the Brotherhood of Steel story line but is removed after the first quest you do for them. It can also be found on a corpse labeled "Man" in the westernmost corner of a ruined building at Freeside's East Gate near Jacob Hoff and across from Mick & Ralph's, which is part of the I Could Make You Care quest line, if choosing the rangefinder.