Small E type soft core ,the material is R2K3D, the power ferrites deries and initial magnetic conductance separately is 5000,7000high magnetic conductance products series. Usage: 1). Power Mn-Zn Ferrite Core for Switch Power Transformer 2). High Permeability Ferrite Core for Pulsing Transformer, Broad Band Transformer, Filiter, Inductance Meter 3). Ferrite core for EMI Components