Gibson Custombucker Underwound Humbucker Pickup, ZebraThe Gibson Custombucker is factory equipment on Gibson Custom Shop's Historic Reissue guitars. After many years of research and development, Gibson's Custombucker offers iconic Patent Applied For tone of 1950s Gibson guitars down to a science. Gibson Custombuckers utilize Alnico 3 magnets which deliver a sweet, warm tone as found on original P. A. F. pickups of the time. It is historically accurate, with its unbalanced coils wound with 42 AWG wire.