Ubiquiti airMAX AM-5G19-120 Quick Start Manual page 11

Hardware Installation
10. The antenna has an electrical downtilt of 2˚. To further adjust
the elevation angle, loosen the two M8x20 Serrated Flange
Bolts on the Slotted U Bracket. Slide the antenna to the desired
tilt. (The upper bracket may slide along the pole, depending
on the angle of the elevation tilt.) Tighten all bolts and nuts
to approximately 14 N-m (10 lb-ft) or less to avoid deforming
the pole.
M8x20 Serrated
Flange Bolt
9