MRT? AMB?Crewe Off Road Club. Transponder help please

[davidmog99]

Hi i want to race at my new local track (crewe off road), opens next weekend.
On the website it says i need an amb compatible transponder. Have seen one on the mardave site for 47 pounds but that is an mrt one, but in the description it mentions amb. I just need to make sure i get the right one.
Also anyone used the shop pro rc in crewe, my satnav cant find it!