MMG India Pvt Limited offers Economical Flat Design - EFD Core. MMG India Pvt Limited is an ISO - 9002 certified company. Economical Flat Design - EFD Core has been developed in recent years to meet the increasing demand for low profile components in power transformer design. A combination of very low height and excellent throughput power, when compared to other cores of a similar height, make these cores ideal where space considerations are a priority. Economical Flat Design - EFD Core is available in a range of sizes and materials together with their associated coil formers and clips.