EF Series Ferrite Cores, Low Loss and High Frequency, Mn-Zn Soft, Used as Power Transformer in SMPS Materials: Mn-Zn, NH2B and NH2C grade (equivalent to TDK PC40 and PC44) Series: EF13, EF16, EF20, EF25 and EF30 E cores have a simple shape Large effective ferrite area Low magnetic self-shielding Available in various sizes Used as power transformer in SMPS EF Ferrite Core