This is a Rectify Series drop-in speaker system for Atlas Classic RS-3 locomotives. The speaker uses a touch of adhesive to mount in the long hood and requires removal of the long-hood 2oz weight.
 
Note that the very early yellow-box RS3s are not Classics and require a slightly different speaker to clear the taller truck-tower. Choose the ALYB-RS3X version for these.
 
The speaker comes fully assembled and tested.
 
Dimensions are: 12mmH x 17mmW x 35mmL
 
VIDEO: https://youtu.be/NMpNJHaTTGo