What is the meaning of the model like EI-5030C and EI-100100?

The EI means EASTIMAGE, it is the brand name and short company name.

The numbers means the tunnel size, 5030 means 50cm W x30cm H, 100100 means the tunnel size is 100cm Wx100cm H.

The last number means different configuration of the same size machine, 5030C, and we also have 5030A, they are different in core parts inside the macines.