This is a set of twenty Pyle National headlights, ten with and ten without visors. Also included are parabolic lenses. Cut them off, polish and clear coat them, and mount an SMD LED behind. The headlight body itself is translucent, which will allow illuminated number boards with suitable decals.
The internal dimensions of each headlight (minus the lens) are 3.78mm diameter x 4.26 mm long.
This is an HO scale, 1:87.1 model of the headlight on Southern Ry. #542, measured by myself in January 2015.