People use it for convenience and pleasant appearance, as the engraved Magen David on it is considered as a sign for strong religious attitude. The origin of this habit is the Passage: "This is my God, and I will praise Him"; exodus 15:2.
The icon known as the Shield of David, which is two triangles integrated together, symbolizes the integration of the Divine with the Earthy.
The triangle which points upward, stands for the materialistic aspects of life, that strives to evolve into the spiritual, while the other triangle, that points downward, stands for the qualities of the Divine which are seeking for the fulfillment through the materialization. The first time the name "Magen David" mentioned as a blessing in the "Talmod": "Baroch ata adonai magen david" King David used this icon on the shield of his warriors as a talisman that wins battles, and by this had been associated with Judaism and as a sign f