It's Trail Air..........
Note arrows. If not in right position, add air at air zerk on top of hitch until it's aligned with arrows properly.
If you want, check air pressure when inflated properly. Each trailer/truck is different. Note that pressure reading and inflate to that pressure anytime air is needed. These Trail Air hitches notoriously leak a little. Not a big deal, just add air.
"Next to prayer, fishing is the most personal relationship of man" Herbert Hoover
"American by Birth, Southern by the Grace of God"Lewis Grizzard
2016 GMC Denali 3500Dually--2017 CC 36CKTS