The Nano Crystalline Cores are made from Iron based Soft magnetic material. These are derived from Crystalline Amorphous ribbon and subsequent heat treatment around 500-600° C .The typical grain size is only 10 nanometers hence the name Nano Crystalline. There appears to be no limitation to the type of cores that can be manufactured from Nano Crystalline material: C-cores, E-cores , Uncased Toroids, Cased Toroids, Multiple cuts Gapped Toroids, etc.