These models had Les Paul's own design of low-impedance pickups, not unlike what he used in his personal Les Paul "Recording" guitar. With two outputs for a hi-fi and low-fi circuit and a phase switch, when used normally it has just one volume and one tone control. I believe the idea behind it was so that the output from the guitar could be cut to half volume so you could crank the amp a bit more to run the tubes hotter.
Unlike a 335, there is no solid piece of wood down the middle of the body, making this guitar very resonant. With epoxy-potted pickups, however, it's not as prone to feedback as one might suspect.
There is a solid piece of what appears to be basswood or poplar under the bridge and saddle, seemingly only to provide a solid anchor for the stud inserts.
Body contour has been achieved by laminating the top and back to slotted solid strips for bend-ability and rigidity.
Overall an inspring guitar to work on and play!