These are Rectify Series drop-in speaker systems for Bowser Executive RS3 locomotives. Two versions are available:
 
The BOWS-RS3S-RC1 speaker is identical in size to the stock speaker and uses the factory mounting screws. No modifications are needed to replace the factory speaker.
 
The BOWS-RS3L-RC1 speaker is a longer version and is secured with a strap of tape over the top. It provides a little deeper sound. No modifications are needed to replace the factory speaker.
 
If you're a fan of dual-speaker configurations, you can nip the mounting ears off of the BOWS-RS3S speaker and it will nicely fit on the chassis under the short-hood with a strap of tape. You can then use the BOWS-RS3L in the stock position under the long-hood. A TCS KA2 nestles nicely behind the control stand if desired.
 
You may need a 2-pin wiring harness to connect the speaker to the PCB. Bowser uses a size (1.25mm) different from the rest of their product line and I stock this size in the PARTS section: https://www.scalesoundsystems.com/product-page/factory-pcb-speaker-harness-medium
 
The speakers come fully assembled and tested.
 
Dimensions are:
BOWS-RS3S: 7mmH x 17mmW x 25.5mmL
BOWS-RS3L: 7mmH x 17mmW x 35mmL
 
VIDEO: https://youtu.be/uCZTq1rbbfs