Ralphie.
Yes, left stirrup. I guess the theory is that when you ride,your feet go out some and create a level surface.
Beats the heck out of me,but it works.
The STI break away stirrup has a latching mechanism on top that is remov ed forn this photo. A stud on each side projects into the top of the stirrup and releases if the stirrup goes too far an angle forward or back.