Magnet accessories are for science experimentation, magnetic properties, quality control.
Certified iron filings, viewing tables and compasses for use with best in class Indigo ferrite bar magnets.
The Mark I magnaprobe uses ultra-low friction jewel mounts for exceptional sensitivity as low as 0.3 gauss. Use it to detect very weak magnetic leaks or the effectiveness of magnetic shielding. Some people have even use it to indicate magnetic declination!
The basic Mark II model is a must for high school physics or electronics classes who want to see the variation in magnetic field shape in the X-Y-Z planes. It is also a very handy tool for aligning magnets. The Magnaprobe's alnico bar magnet has N & S red-blue painted poles so you can use it to line up all your magnets so that their poles face the same way.
Magnaprobe™ is a trademark of Cochranes of Oxford, UK. If you see a similar black, red or green handled version selling for <$10, it is a cheap knockoff from "you know where"-caveat emptor.
Magnaprobes use gimbal mounted bar magnets to find poles or detect magnetic flux. The Mark I is ideal for testing magnet shield effectiveness.