9840 or 9845?

Not sure if this belongs here but does anyone know how to tell the Simplex 2901-9840 and 2901-9845 apart from each other? They appear to be the exact same horn.

According to this page the 2901-9845 is the 100dB version of the 2901-9840.

So I probably shouldn’t go off the color of the diaphragm. I always thought the 9840s had a black one while the 9845s had an unpainted one.

I’m honestly not sure why some horns sometimes have black diaphragms & other times silver ones.