what is the width at the top of the 12 ft. Galvanized Steel High-Hat Furring Channel?

The top of the "hat" is between 1-1/4" - 1-1/2" depending on the manufacturer.

The top of the "hat" is between 1-1/4" - 1-1/2" depending on the manufacturer. The 2-3/4" refers to the base width and it is 7/8" high.