I just bought a used RRS L bracket, model#BGE11-L for my 5D-lll, and wanted to know if anyone can let me know, if I need an additional plate to use the camera vertically, If you use this please let me know? Best regards rbtstock
The short answer is yes, as an "L" plate it would have an arca-swiss compatible mount on both axis of the L, so if it says it is an L plate in the description you should be able to find both mounting plates on the bracket. I found an image of your model to use as an example.