Ender IO's unit of Energy is called a Micro Infinity, and is annotated by µI.
In practice, Ender IO uses the Forge Energy (FE) API; Micro Infinity is another label for it, similar to Actually Addition's Crystal Flux and Immersive Engineering's Immersive Flux.
In general, Forge Energy converts 1:1 with both the CoFH RF and Tesla APIs, but the power conversion has to be done using another mod. Note that the CoFH mods (the Thermal series) handle the RF <-> FE themselves and encourages other RF mods to do so as well.