why spent money buying one when u can diy
most existing plug are made of iron, as u have learn from school, anything that is metal can be magnetize
find a really strong magnet
then rub the magnet across the plug/screw in one direction for as many time as u wish until it become magnetize
for me i do this when i change my engine oil after i took out the plug
using this method save money and will let your magnetize plug stick onto metal debris in the future
most gear box plug is magnetized, wonder why oil plug is not, anyway, enjoy your DIY