As Gonzo Bob has pointed out it seem to be the SRM-Powermeter unit with comes with various crankarms such as FSA Gossamer or others. All the compact SRM powermeters are using 130BCD for the large chainring ring and a 110BCD for the small ring. So for everybody who does not know, or has not seen, (or does not underrstand), just look at Gonzo Bob's picture and description above or study the SRM site. http://www.srm.de/index.php/us/power...ssamer-compact