NEC FA Series Installation And Maintenance Manual page 61

The arrows (↑) at the back of the pixel cards indicate the upper side.
Install the pixel card into the cabinet with the four guide holes of the pixel card aligned with the four guide pins
of the cabinet (four pins for each pixel card). The pixel card is secured by the 4 magnets on each pixel card.
Insert into the guide holes
4 magnets interface
4 magnets
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