This is a Seymour Duncan APTL-1 "Alnico II Pro" Bridge pickup for Tele.
Alnico II magnets are the musical magnets.
Their softer magnetic field provides a warmer, sweeter tone and eliminates the brittle,
glassy sound associated with newer instruments.
The result is a more natural string vibration for true tones with greater sustain.
Working closely with pro musicians...
Seymour developed the APTR-1 for discriminating Tele players.
The Alnico II Pro Tele Lead uses a vintage coil wind, and sand-cast Alnico 2 rod magnets for a vintage Telecaster pickup sound and vibe, but with a smoky sweetness on the high end. You’ll still feel the Tele snap and twang, but with a nice, round warmth added in. Your pick attack will feel slightly mellower, and chords will have a spongy, bouncy quality.