Alternating thick/thin magnetic poles provides best holding power for both thick and thin workpieces. EDM-Ready, fully submersible, brass welded faceplate. Faceplate is machineable and protects the magnetic system from coolant. Powerful Rare-Earth Neodymium Iron Boron Magnets are 5 times stronger than other magnets. Needs no electricity. Low-profile design increases Z-axis stroke. Housing and bottom plate are free of magnetism - will not magnetise machine bed or bearings.