... could make custom-design transformers according to your requirement.Various bobbins as below:EE5,EE8.3,EE10,EE13,EE16,EE19, EE22 ... RM12/RM14 series bobbins PQ1616 to PQ5050 series bobbins EFD15,EFD20,EFD25,EFD30 series bobbins EPC13,EPC19,EPC25,EPC30 series bobbins EP7,EP10, ... .5 SMD series bobbins EI22 to EI50 series bobbins Toriod cores case and base holder series bobbins ET series bobbins UU.8/UU0 ...