I'll answer my own question in case anyone else needs the info...16x same as the II's without removing the pin. One can remove the pin and clamp the head to the top of the column which will give you a full 16x20. The XL post is needed for anything larger.
Ignore that last post. I read the scale wrong it should be 10x for the IC where my IIA can enlarge to 13x without moving the head up the post. Thats what you get for trying to read in the dark.