Transponder help!

[tdi250]

Hello,

Excuse me if this is a daft question but i'm only just gettign back into 1/10th off road.

I want to race at the regionals this year (midwest) but don't have a personal transponder.

I've been looking at the MRT ones but i'm unsure about how it all works.

Do i have to get a "unique" number from somewhere to put on the MRT ones? If so where do i get this from? Or can i just buy one and go racing?

Please help, confused!
Wes