Despite not being able to find anything similar using a quick google search, I am 99.99% certain that these are EMI suppression filters.
They are T section filters with two inductors in series with the line where the suppression is to be done, and a capacitor from the junction of the two inductors to earth.
The inductors may simply be ferrite beads on a length of wire.
The filters stop RF noise from entering and leaving the equipment on which they are installed.
In the photo in the link, notice that there are a group of these devices connected to the circuit tracks going to/from connector CN3, one of the devices seems to be physically broken.
JimB
On edit:
Cobra1 has found them!
(while I was messing about doing other stuff)