I just took the tubing into a machine shop this morning and the OD is .125". They've got boxes full of hundreds of precision cylindrical pieces of metal, in increments of .001", that are used to measure inner diameter. The tubing has an ID of .088.
I use this for my bikes at friction points, but they are not Klein bikes. It works with the old thick brake cables as well as the thinner shifter cables.
Conversion to inches OD = 0.1185 inches ID = 0.102 inches. Again my measurements are approximate because the tubing is not completely round. I tried to get the best average reading.
I will try to go to my source and look at the reel later today, maybe it has the actual dimensions on the reel.. It is fairly inexpensive I seem to remember somewhere around 10 cents to 50 cents a foot no quanitity minimum. Available in black as well.