I have an older Nolting long arm. There is only one foot for it and I believe it is called a Hopping Foot. I have to buy 3/8" thick rulers. The 1/4" are too short. That's if I want to use the ruler as a guide while I am quilting. Now, if I want to use the rulers to mark a pattern on my fabric and then freehand the sewing I can use any size rulers.
The assumption for most quilting rulers is that they are 1/4" in thickness. These are 1/4" thick. They would be good design rulers for me, but not sewing rulers.