Just arrived from my friend Vito's collection, this CD 122 VMR NAPOLI in the top groove version (right side). The threaded part of the speciment with top groove is a bit shorter than in the other original (without top groove) version. If you want to know the story of this insulator, you can read it clicking to the picture posted by Shaun Kotlarsky a few days ago. Thanx, Vito, it's been a great deal!