One of the "oddity" sizes of bar magnet - sometimes turn up in P90s, sometimes turn up in Mini-buckers, very rarely, even in full sized humbuckers. As always, worth checking the sizes to make sure this is the one you need.

These are the bar magnets commonly found in Gibson® firebird mini humbuckers - used as a magnetic pole within the bobbin, resulting in a very different tone.

Oversized bar magnets usually turn up in higher output pickups, and are a fantastic way to get a really unique tone.