Look for the 'white paper' on mylaps site. If you read it, you will see that the new transponders are backwards compatible with RC2 and 3 decoders, obviously working with RC4 decoders. RC3 Decoders can be upgraded to RC4 standard.
Likewise, the RC4 decoder will read RC2 standard PT's. The ones we have now.
The link is on this page.. Enjoy the read..
http://www.mylaps.com/index.php/emea...w_standard_rc4