Optical Shaft Encoder

How thick is the optical shaft encoder?

My understanding is that it is 2 5/8 inches long and 2 inches wide with the shaft hole 1.5 inches from the screw holes, but how thick (deep, tall) is this sensor?

It is a brief question, thanks in advance

CAD drawing shows about 0.8 inch.

Physical measurement of an actual sample, using a 25’ Craftsman steel tapemeasure, or a 99cent (on sale) Harbor Freight plastic caliper, show a thickness of 13/16 of an inch.