The second series was developed as a miniature version with a much smaller E4.2 core. Its primary winding is integrated in the coil former in a space-saving way. This series needs only 33% of the area and 23% of the volume (4.7 x 3.5mm² and insertion height 3.5mm) of their EE5 counterparts. The design of the series enables inductances of between 33 and 1280μH, DC resistances to 2.5mΩ, 7A current rating, and a test voltage of 360V AC.