SUB-MINIATURE FERRITE BEAD
These were a specially produced item for Racal for use in military equipment, they are a very small ferrite bead.
We have no idea of the ferrite composition, they are coated in some kind of metallic coating.
Owing we guess to the small size and the way they were manufactured, the sizes are not exactly uniform, generally they are between 2mm and 3mm outer diameter with an inner diameter of about 1mm, length is about 1.5mm.
Priced and supplied in packs of 10 pieces