How do I calibrate this gauge to atmospheric pressure

What tools are required for this swap

25 inch extended shank (3-1/4")

This package includes a rugged Handibox

Built as a low-voltage heating control

Schneider Electric (Barber Colman) AM-764 Kit Els PW 17895 How do I calibrate thisWhen you're outfitting commercial HVACR units with Schneider Electric damper linkage kits, the Barber Colman AM 764 is the industry standard for bridging the gap between a damper actuator and the drive shaft. This heavy duty damper linkage kit is engineered for technicians who need a reliable mechanical connection when direct coupling isn't an option. The AM 764 damper linkage kit features a robust actuator crankarm and high grade ball joints designed