Bulk is the solid enclosure in which optical attenuator is packaged.Shipping overseas is convenient with the RF Attenuator packed in 0805 (2012 Metric).
E-TA2012 10DB N3 Features
E-TA2012 10DB N3 Applications
There are a lot of Nidec Copal Electronics E-TA2012 10DB N3 Attenuators applications.