This is a Rectify Series drop-in speaker system for Auscision SA 600 and NSW 45 Class locomotives. It may fit other models as well.
For the SA 600 Class that I worked on, I used a dual-speaker configuration by adding a front-mount UFIT-2318 speaker in the short-hood.
The speaker comes fully assembled and tested.
Dimensions are: 10mmH x 16mmW x 35mmL