Profile: Custom Coil & Transformer Co. specializes in coils and transformers. Our product line includes Endbell & current transformers, coil & air core inductors. three phase and bobbin transformers. Our Endbell transformers are used to protect the windings in harsh environments, as well as, providing protection for users that may come in contact with the transformers. They provide shielding for special applications, such as audio amplifiers and power supplies. Our current transformer is used in monitoring & measuring applications to measure high current. The high current primary connection is usually stepped down to a smaller current that can easily be measured.