This is a Rectify Series drop-in speaker for Bachmann ALC-42/SC-44 Charger locomotives. The LLPR-ESFR-RC1 speaker will fit in two locations. Location one is right in the middle between the stock PCBs. Option two is nestled in the rear cavity of the chassis. You can use one speaker in either location or a dual-speaker configuration occupying both spots.
 
The speaker comes fully assembled and tested.