The main reason for the reduced size and increased efficiency of the toroidal transformer is the highly efficient core. The core for the toroidal transformer is wound with one continuous strip of silicon steel. This results in a core with no gaps. The core of the laminated transformer is stacked with numerous laminations which results in gaps in the core. The gaps add to the overall core losses. Also, in the toroidal core, the magnetic field flows in the same direction as the grain orientation of the steel. That is not the case throughout the entire core of the “EI” type transformer.