I was going to post a "let me Google that for you" link here, but a direct answer would be more efficient. It's an in-ear earphone made by Sony.
I haven't heard those before but looking at the Innerfidelity charts, I think the M-100 would be more balanced-sounding compared to the MH1C's; the MH1C looks like it would be a bit darker in presentation compared to the M-100. If anything, the Shure SE215 has a similar sound signature to the M-100 but with much less sparkle and a smoother midrange.
Edited by miceblue - 5/19/13 at 7:20pm