Handheld deburring / reaming tool.
This tool is the Best option I have found to easily and precisely remove the sharp edge on the inside of the gauge port opening.
To prevent air leaks, removing the sharp edge keeps the o-rings on the valve assembly and the gauge port from being nicked during their installation.
Directions: Rotate the blade of the reaming tool clockwise around the entire inside sharp edge of the gauge port opening 3 to 4 times.
Also great for removing the sharp edge from other products too.