Understanding some basic characteristics of guitar pickup components, such as magnet types and DC resistance, may help one narrow their search within the wide variety of pickups available. There are many other aspects that can help determine a pickup's overall sound, but the following information should help in making an informed decision. Wizz Alnico magnets are made in United Kingdom.
 
Alnico 2
Warmer sounding with less magnetic pull to allow the strings to vibrate more freely. A good choice for warming up a bright or harsh sounding amp and guitar. Overall the Alnico 2 is warm, with clear mids, spongier bass, and a softer attack. Many players use the Alnico 2's to better achieve the vintage tone heard in many pickups from the 50's era.

Alnico 3
Considered to be brighter than Alnico 2 with the least magnetic pull to allow the strings to vibrate more freely. A good choice for clean tones and lots of articulation. Overall the Alnico 3 is bright, with clear mids, warm bass, and a softer attack.  
 
Alnico 4
This magnet is best described to have the characteristics of both Alnico 2 and Alnico 5. Kind of a happy medium.

Alnico 5
Bright sounding with more focus and enhanced dynamics. A good choice for adding a brighter punch to a warm or dull sounding amp or guitar. Overall the Alnico 5 is bright and punchy, with glassy highs, tight bass, and more attack. Alnico 5 magnets are the most commonly used magnets in guitar pickups today.