Ubiquiti airMAX AM-5G20-90 Quick Start Manual page 8

8. To mount the antenna to the pole, slide a Pole Clamp over
each pair of Carriage Bolts. Secure each Pole Clamp with
two Serrated Flange Nuts.
Note:
Ø 38 - 76 mm (1.5" - 3.0") pole.
The mounting assembly can accommodate a