VX/256 Expansion Chassis are 19″ rack mounting units, 5.25″ high and 15.6″ deep, built with power supplies and motherboards that hold up to 16 VX Switch Modules. Switch modules plug into the chassis so that signal I/Os are accessible on the rear panel and the LED display is visible through the front panel. Mainframe chassis hold any of the VX Series Switch Modules.

link to switch module selector