There are currently three ARRI rod standards; 15mm LWS lightweight Support , 15mm Studio, and 19mm Studio.
But rods are rods right? NO!! Just ask one of the American manufacturers who have a sea container full of rods they believed to be industry standard… They are now called looking at rods.
So here is an overview of the rod standard chart available on the ARRI Pro Camera Accessories website.
See more on the ARRI website.