2014 Outback 3.6R - which serpentine belt?

[ChiTDI]

2014 Outback 3.6R
Rock and Napa both list two different serpentine belts.
Both say “Fits your car”.
6PK1625
6PK1650

Anyone have any experience or thoughts on this?
Also, it appears the system has only one replaceable idler pulley along with the tensioner.
Am I missing something?

 

[SilentType]

Are all accessories driven off of one belt many cars have separate AC compressor belts?

 

[D60]

That's crazy because 25mm is an inch, which is a lot in belt length. If it were ~1/4" I'd say it doesn't matter

Failing matching your existing belt, I might try a site that can tell you based on your VIN

 

[Kira]

The Dayco site says 6PK1625.