Like many of us, there are many rare insulators I have never seen before. The best I can do is use my imagination and a little help from good old modern 3D rendering. I created the 3D image of the CD 289.9 from the cut away drawing of the insulator on the right. Unfortunantally the drawing gets confusing on the lower groove. I made the assumption that the groove is only on 1/2 of the insulator and slopes up to the non-grooved side instead of being a hard jump. I am by no means a 3D expert so the model is a little rough...

Here is a short video of it rotating for clarity: (34k)

http://www.bensdomain.com/289_9.wmv

Has anyone seen a CD 289.9 up close before? Did I get the lower groove right?