There is a Bulk solid enclosure around the optical attenuator.Due to its 1206 (3216 Metric) packaging, the RF Attenuator is convenient for international shipping.
E-TA3216 5DB N8 Features
E-TA3216 5DB N8 Applications
There are a lot of Nidec Copal Electronics E-TA3216 5DB N8 Attenuators applications.