Langevin (SoCal) true vintage rotary pot dual ladder format, cylinder body. I think there was a yellow/red label long ago that fell off and was lost. 

~20 step smooth rotation (no detente); has taper to "off" cue function. 

Typical 1/4" shaft. Nominally 150/300 ohms. might have been part of a Gates Radio console or outboard unit. 

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