This is the frame around which the wire is wound on a pickup. The term is most often used when discussing coverless humbucking pickups or humbuckers that had their covers removed. All of Gibson’s humbuckers originally had two black bobbins in each pickup, but in the late 1950s, the company’s supplier of plastic ran out of black and substituted cream plastic. Once it became fashionable for guitarists to remove the nickel covers, they discovered that some pickups had two cream bobbins, while others had one black and one white, leading to the term “Zebra Coil.” As usual, overly obsessive collectors convinced themselves that guitars with zebra bobbins sounded better — a fact that has never been proven.