8163A/B, 8164A/B, 8166A/B User’s Guide 353
Accessories 12
Keysight 81645A Filler Module
The Keysight 81645A Filler Module is required to operate the 8164A/B
mainframe if it is used without a back-loadable tunable laser module. See
Fitting a Filler Module for Back-Loadable Module Slots on page 334 for
more details.