The tremolo system is made from an old hardened-steel knife-edge shaped into a V and two motorbike valve springs to counter the string tension. The tension of the springs can be adjusted by screwing the bolts, which run through the middle of the springs, in or out via two small access holes next to the rear strap button. To reduce friction, the bridge was completed with rollers to allow the strings to return perfectly in tune after using the tremolo arm (the arm itself was from a bicycle saddlebag holder with a plastic knitting needle tip). For the same reason, at the other end of the neck the strings pass over a zero fret and through a bakelite string guide.