Rawlings Power Balance Performance Bracelets Power balance holograms are embedded with frequencies that react positively with your body's natural energy fields. When the hologram comes in contact with your body's energy field, it allows your body to interact with the natural, beneficial frequency stored with the hologram. This results in improved energy flow throughout your body. Size: Small - 7", Medium - 7.5", Large - 8", XL - 8.7".