This is a term used by Seymour Duncan to describe humbucking pickups that have a slightly wider bobbin and wider pole-to-pole spread. These are specifically meant to be used as replacement pickups on guitars that are equipped with Fender-spaced or Floyd Rose-style vibrato tailpieces. The string spread on such guitars is slightly wider than that of guitars Tune-o-matic or similar bridges. On standard humbuckers, the bobbins typically measure 2.695 inches, while “trembuckers” typically measure 2.780 inches. String spacing on a regular humbucker is usually two inches or less, while a Trembucker can accommodate spacing of two inches or larger.