For Sale: SRAM SRM Wireless Powermeter. Can use with Garmin or SRM Powercontrol (not included). Unit is for GXP bottom bracket, has 172.5 cranks, and has 39/53 chainrings. Unit bought in 2010. great condition. May be able to sell with different crank length if you are willing to wait.
PM me with more questions.
PM mw with e-mail address for pics.