Her biggest wish was to protect her child from evil, and because of this she is remembered as a sacred mother figure. Along these lines, a ceremonial custom was created in which a red string is tied around Rachel's burial chamber multiple times to inject it with the energy of security and good karma. "In the wake of opening up the string from Rachel's burial chamber, it is then cut into arm band estimated lengths and tied onto the wearer's left wrist while recounting a petition for security. It is accepted that the arm band will at that point protect one from evil." (Kabbalah .com)
According to the chakras of the body, the "left arm is involved with the future or energy coming toward you and your physical body." The energy from the left center determines what incoming energy you are able to connect with and use. "It literally chooses what you want to use to create your every moment and pulls energy up the arm so you have the necessary energies to create change..." By placing the red string on the left hand, you are, in a sense, protecting your energy! The color red addresses the desire to receive and the left addresses desire to receive in this way.