There is a Tape & Reel (TR) solid enclosure around the optical attenuator.This RF Attenuator is conveniently packaged in 1206 (3216 Metric), making it easy to ship abroad.
E-TA3216 T 4DB N5 Features
E-TA3216 T 4DB N5 Applications
There are a lot of Nidec Copal Electronics E-TA3216 T 4DB N5 Attenuators applications.