WE-FSFS Flexible Sintered Ferrite Sheets Würth Elektronik WE-FSFS Flexible Sintered Ferrite Sheets provide high permeability and low losses. These flexible ferrite sheets feature easy-to-apply adhesive mounting tape. This series is ideal for improving the efficiency of wireless power transfer (Qi-WPC, PMA, A4WP, WCT), improving the performance of NFC and RFID communication systems. Additional applications for Würth WE-FSFS sheets include EMI suppression and magnetic shielding.