The wiki as well as other searches show the latest 15X firmware as 1.03.0, however, I recently purchased one with 1.05.03 and would like to bring the second scanner up to the same.
From the wiki:
What are the most current firmware releases for the trunktracking radios?
Model Firmware Version
BCT15X 1.03.00
Screenshots of both 15X's:
From the wiki:
What are the most current firmware releases for the trunktracking radios?
Model Firmware Version
BCT15X 1.03.00
Screenshots of both 15X's: