The ring object is circular, with a specified outer radius and thickness, and with its center given by the pos attribute:
The ring object has the following attributes and default values, like those for cylinders: pos (0,0,0), x (0), y(0), z(0), axis (1,0,0), length (1), color (1,1,1) which is color.white, red (1), green (1), blue (1), and up (0,1,0). As with cylinders, up has a subtle effect on the 3D appearance of a ring. The axis attribute only affects the orientation of the ring; the magnitude of the axis attribute is irrelevant. Additional ring attributes:
radius Outer radius of the ring, default = 1
thickness Thickness of ring (1/10th of radius if not specified)
Note that the pos attribute for cylinder, arrow, cone, and pyramid corresponds to one end of the object, whereas for a ring, sphere, and box it corresponds to the center of the object.