Sowter attenuater transformer volume control. From their website:
"The transformer action of these attenuators assures the loading circuit sees a low driving impedance regardless of switch position. This ensures the maximum bandwidth potential and minimum distortion of the circuit can be realized at all gain settings."
"The transformer action of these attenuators assures the loading circuit sees a low driving impedance regardless of switch position. This ensures the maximum bandwidth potential and minimum distortion of the circuit can be realized at all gain settings."