3 x 2 pieces of colored rubber bands are included with each lithium pack. These can be used to help identify multiple lithium packs that are paired with the Lenz heat app. For example, the lithium packs for the heat socks and the heat vest can be color coded. The rubber bands are placed in the middle of the lithium pack so that they cannot slip. Furthermore, the lithium packs can also be marked per person, e.g. if several people in a family use lithium packs.