Magnetic therapy is an alternative medical practice that uses static magnets to alleviate pain and other health concerns. Therapeutic magnets are typically integrated into bracelets, rings, or shoe inserts, though therapeutic magnetic mattresses and clothing are also on the market. 

Magnetic therapy dates back at least 2,000 years. Healers in Europe and Asia are believed to have used magnets to try to treat a variety of ailments. These healers believed that magnets could actually draw disease from the body. 

There are many companies that sell therapeutic magnets that place a small magnet inside of a bracelet or other device to help increase blood flow to the area of the body where the device is worn. This increased blood flow is then said to help tissues heal faster. 

The most commonly used therapeutic magnets measure 400 to 800 gauss (one of the units in which magnet strength is expressed). Also known as permanent magnets, the static magnets used in magnetic therapy devices come in two different polarity arrangements, according to the Langone Medical Center report. The magnets are either unipolar, which means they have north on one side and south on the other, or they are alternating-pole, which means they are made from a sheet of magnetic material with north and south magnets arranged in an alternating pattern. 

Resources: https://www.livescience.com/40174-magnetic-therapy.html