The Hebrew word for "Life" is חי CHAI, which has a numerical value of 18. Consequently, the custom has arisen in Jewish circles to give donations and monetary gifts in multiples of 18 as an expression of blessing for long life as 18 is considered a blessed number because of it is the numerical value ofחי In Judaism, in the Talmud; Pirkei Avot (5:25), Rabbi Yehudah Ben Teime gives the age of 18 as the appropriate age to get married ("Ben shmonah esra lechupah", at eighteen years old to the Chupah (marriage canopy)). (See Coming of age, Age of majority). Each pendant comes with 2 chain a silver 925 chain necklace 16"(45cm) , Leather necklace with metal clasp and gift box . Size: 20mm X 16mm (0.78 X 0.62 Inch) thickness: 0.7mm / 0.03Inch Material: Silver 925 Type: Pendant Enjoy Your Shopping!