|For an overview of slave collars throughout the Fallout series, see Slave collar.|
Deactivated bomb collar
These bomb collars were presumably deactivated and left behind by Elijah from his stay at Big MT. Once he discovered how the collars work on radio frequencies, he took a few bomb collars with him to the abandoned Brotherhood of Steel bunker and forced people to crack open the secret of the Sierra Madre.
They are located in the Little Yangtze watch tower. Once you enter the Little Yangtze watch tower, there are some located on the desk directly front of you. There are also some on the counter behind the desk and some on the shelf as well.