This is a Rectify Series drop-in speaker system for all Athearn RTR SD38/40/45 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 uses the factory mounting screws and no modifications are needed to replace the factory speaker.
 
An optional front-mount speaker may be added to many of these locos. This speaker is designed to replace the small weight (Athearn part #88550) that I have seen used in RTR SD38s and SD40s and has dimples to accommodate the screw-posts. A bit of double-sided tape or a dab of adhesive secures it. It is not recomended to use the front-mount speaker alone.
 
The speakers come fully assembled and tested.
 
Overall dimensions are 18mmH x 18mmW x 47mmL
 
VIDEO: https://youtu.be/45GzKmzPpMg