The Controller No. 390C was originally designed for use in reversing electrical polarity on HO reversing loops of track and was first illustrated in the 1959 HO portion of this year’s catalog. It was soon realized that it’s usefulness went beyond this purpose, and beginning in 1960 until 1964 it was shown in the O Gauge section of the catalogs. This double-pole double-throw switch could, for example, be substituted for the No. 148-100 that was included with the No. 148 Dwarf Signal.
The inclusion of the envelope in good condition is required to obtain "Like New" condition. There are two variations:
Variation A: Has a RED sliding switch.
Variation B: Has a BLACK sliding switch. This variation is considerably rarer.