CD 579 large V.W. on the crown -- Although this insulator does have some base damage with a 2" flat chip on one side a s a smaller chip on the back with a 1" vertical fracture up the skirt. What makes this insulator unique and rare is both the scarce V.W. (Vitrum Wołomin glass co.) and the green with amber swirling! This is the only one like this I have seen. looking for $45 plus actual postage.