WE-CBF SMD EMI Suppression Ferrite Beads Würth Elektronik WE-CBF SMD EMI Suppression Ferrite Beads can be placed directly on a printed circuit board and offer excellent anti-EMI properties and low DC resistance. Even if positioned extremely close to a source of interference, these beads can reach maximal impedance at 1000Ω. Würth Elektronik WE-CBF SMD EMI Suppression Ferrite Beads are available in a range of sizes, including 0402, 0603, 0805, 1206, 1210, 1806, 1812, and 2220.