For those interested, I contacted Mylaps about what MRTs would work for the trade in offer, and this is the reply I received.

Hello,

Any MRT qualifies. Just note: The $35.98 trade in offer will get you the new RC4 transponder; however, these are not available until February. they are on backorder currently, but if you want one, go ahead and put your order in now! And send us your MRT's as soon as you can. Or you can place an order for the MRT to RC4 Hybrid trade in for $80+ and you can receive a transponder within the next 2 weeks.

Either way, please make sure you send in the MRT first before we will ship out the new Mylaps transponder.

Regards,
Kelly Chase
Sales Consultant