They are 1/2" diameter. I still have my old set
I changed out last week.

If you are replacing yours keep this in mind.

I bought a set and they are only bent into a U shape. The original set I took off are also
flattened in the U area and have some Grippers formed in there also. I am afraid I bend or crushed
my axle tube some with the new ones. For what it's worth.