This means that the speed of an electrical signal traveling through RG-59 cable is about 66% of the speed of light in a vacuum.

Important Note:

* The velocity factor can slightly vary depending on the specific construction and dielectric material of the RG-59 cable.

* For accurate calculations, it is always best to consult the manufacturer's specifications for the specific cable you are using.

Let me know if you need further information about RG-59 or other types of coaxial cable!