This is a Rectify Series drop-in speaker system for Walthers Proto E-Unit locomotives (and possibly late-run P2K). It has a slight oblong egg-shape that fits perfectly within the frame's cavity and a domed top following the roof's contours. 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. Usually used in pairs, but can be used singly as well. No modifications are needed to replace the factory speakers.
 
The speaker comes fully assembled and tested.
 
Dimensions are: 30-32mmDia x 14-16mmH