This is a Rectify Series drop-in speaker system for MTH GP35 locomotives. More than just a box, the enclosure features Diapasonic Tuning™, which allows the lower frequencies to accurately develop and resonate, clears the midrange of excess resonance and tunes the upper-mid/high response. The speaker nests into the frame and requires removal of the DCS decoder and either a Decoder Buddy or hardwire decoder installation.
 
The speaker comes fully assembled and tested.
 
VIDEO: https://youtu.be/uy1a75jGprw