Cheap And Discounts Fe3O4 High Purity Powder 99.9% Black Magnetic Iron Oxide for R&D Ultrafine Nano Powders About 10 Micro Meter 100 Gram Wholesale. Buy Directly From Merchant LOLO Store. Enjoy ✓Free Shipping Worldwide! ✓90 Days Buyer Protection. ✓Easy Return. ✓Money Back Guarantee.