SRAM Rival Rear Derailleur Cage Size?

[sunchaser]

Hi guys, how can I determine if I have a short or mid cage SRAM Rival rear derailleur? Can I measure it or is the size on there somewhere?

 

I want to "upgrade" to 11-32T (cassette), and I think this requires at least a mid (medium) cage (the short one maxes out at 11-28T)

 

Thx.