Photo of the Hebrew letter Vav inside a Star of David painted on an old tile is courtesy of Mr. Abraham Madeisker from Trionfo Judaica Store, 9 Dorot Rishonim St.,Jerusalem.
Vav is the third letter of the Divine Name. It has many meanings, i.e. it is a hook that connects the opposites (like the interlaced triangles of the Star of David). Its numerical value is six (like the six triangles built around the hexagon in the Star of David).