Transponders - confused please help ?

[brown4s]

Can someone please help with explaining my options with which transponder to purchase. I will be starting off in 2wd but may add 4wd at a later date.

Just checked my soon to be club (Coventry model car club) and they have posted this message:

CMCC are changing over to RC4 at the first round of the summer series on 6th April, all AMB or Mylaps PT’s will work with this system with no guarantee that MRT’s will work.
Summer series has been split this year with a 4 round astro series( all Classes on the Astro) and a 4 round Dirt Series(1/8th on the dirt and 1/10th on the Grass), dates as per the club calendar.