If your ST-4000i is on an annual calibration schedule with American Aerospace you will always have the latest firmware and app version. Effective January 2020 the latest Firmware & App version is:

Firmware 3.2.0.6
App 1.3.8

We recommend a calibration service every 12 months. For current pricing on calibration services for the ST-4000i please complete the following request. We can also be reached at [email protected].