PRESONUS NSB Series Owner's Manual page 36

Replace the extra screws in the unused holes to avoid losing them.
For a reversed configuration, simply rotate the ears 180° and re-attach the screws.
3. Mount your reconfigured NSB 32.16 stage box in the rack of your choice. You're done!
4.5 Configurable Rack Ears (NSB 32.16 only)
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