This is a Jbl 2440 Driver with a JBL 2385A Fiberglass Horn. Label says 16 ohms but my meter reads 8.0 ohms. So I think the diaphragm in not original. The foam in side the cover should be replaced. 

The horn measures 17.5 x 10.98" or 445mm x 279mm

FROM THE INTERNET:

Flat front biradial horn developed as a small and lightweight type.

The throat diameter is 49 mm.

It can be flash-mounted in a speaker cabinet or used for compact cluster configurations.

The directional control in the horizontal plane is designed with precision to prevent narrowing in the mid-range and beaming in the high-range.
Furthermore, by stacking multiple horns, it is possible to control the orientation of a vertical plane comparable to that of a large horn.

Because the overlap of the horns is minimal, you can eliminate the effects of roping and comb filters.

2380A, 2382A, 2385A a, and 2386 with different coverage angles have a common opening size at the time of mounting.