the amb ones are normally a little larger, except for the new Harry ones, and are made by the same people who make most of the systems, the mrt are normally a little smaller. I have use both the amb in my 8th and the mrt in the 10th and have had no trouble with either, i will say that the mrt ones come with the ability too change the transponder number though if it ever happens that someone has the same number as you.
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