Bit Char-G's and Microsizers are the same, they just changed the name for us Americans because we are too dumb to figure out that a "Bit Char-G" is not part of your complete breakfast.

"I like to pour milk over mine and throw in a few slices of banana!"
Microsizers are only available in 2 frequencies, because that is all the FCC will allow them. Bit Char-G's are available in 6 frequencies, but the FCC doesn't like that and they are pressuring American retailers not to carry the "ODD" frequencies, so get 'em while they're hot.