UnderWood Pickup / For Upright Bass

This is a pickup for Underwood (アンダーウッド) double bass (wood bass).
It is a type that is installed in the wing slot of the bridge.
Purchased new in the late 80s, it has only been used at home, but the exterior has discolored with age. The instruction manual and case also have discoloration and tears.
The sound outputs properly. It has a clear, cutting tone.