53A-850 EXTENDER CARD
The 53A-850 Extender Card is used to allow a systems, chaining, communications, or control card to be extended its full length from the mainframe to facilitate service or calibration. The Extender Card is usable in any of the 13 slots in a 53B mainframe or any of the 8 slots in a 63B mainframe or 64B mainframe.