Easy to apply around the cables.
Can be closed with a Velcro zipper or self-closing.
No mess to fiddle with the cables through a sock.
The diameter is the 'diameter' of a circle.
That centerline is a line going from one side of the circle to the other, through the center of the circle.
The radius is half the diameter, so the distance between the center and the outside of the circle.
Nice product from Bosscom delivery in four length.