Only IVY Classic® Screwdriving Sets contain the Mega-Magnetic® Bit Holder with its patented two magnet design creating 40x the pulling power of ordinary magnetic bit holders. Patented in the USA. Magnet #1 holds and magnetizes the bit while magnet #2 powerfully holds your fastener in place! All insert bits made of S2 tool steel. Rockwell hardness 60-64 HRC.