PAF

This stands for “Patent Applied For.” When Gibson began installing humbucking pickups in their high-end Les Pauls in 1957, their patent for the design had been applied for, but not yet granted. Thus from 1957 to about 1960, Gibson humbuckers have a small black sticker on the underside that says, “Patent Applied For.” Over the years, these early humbuckers achieved a cult-like following. Many guitarists swear that these early examples are the best pickups Gibson ever made and that their tone is somehow preferable to later versions despite the lack of any hard evidence to support this.