152.4 x 101.4 x 25.4mm thick Y30BH Ferrite Magnet - 8kg Pull
Ferrite (Ceramic) Magnet Material | Eclipse Magnetics
Amazon.com: Ferrite Ring Magnets with Holes - 1.38 Inch (35mm) Round Disc Donut Magnets for Refrigerator Fridge, Science Projects, Crafts, Around The Office (Pack of 30) : Industrial & Scientific