Seymour Duncan STK-P1 Stacked P-90 Single-Coil Pickup Cream Bridge Unlike other single-coil P-90s, the P-90 Stack is a true humbucker in a P-90 package Using Duncan's patented Stack technology together with adjustable pole pieces, the guitarist can now obtain great P-90 tone in a studio-quiet pickup Using Duncan's patented Stack technology together with adjustable pole pieces, the guitarist can now obtain great P-90 tone in a studio-quiet pickup