Transponders

[MrB]

Hello, my Son is racing a Mardave at a local club. We are using the clubs provided Transponders but have had at least 3 failures in a couple of Months. Last night he won a Final but he diddnt record a lap. He is 11 so could do with him enjoying a rare victory.
So i see 2 types the AMB and MRT. The latter is cheaper so is it inferiour? and basically can anyone tell me the differences. Thanks for your time. Chris.