You will get four options there and below Aruba gave description for those:
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disable: Disables ARM calibration and reverts APs back to default channel and power settings specified by the AP’s radio profile
maintain: APs maintain their current channel and power settings. This setting can be used to maintain AP channel and power levels after ARM has initially selected the best settings.
multi-band: For single-radio APs, this value computes ARM assignments for both 5 GHZ (802.11a) and 2.4 GHZ (802.11b/g) frequency bands.
single-band: For dual-radio APs, this value enables APs to change transmit power and channels within their same frequency band, and to adapt to changing channel conditions. Default: single-band.