Find your favorite ring and use a ruler to measure the internal diameter of the ring.
To determine your desired length, choose where you want the disc to sit on your chest. Take a string and wrap it around your neck—holding it at the desired length. Then, take the string and measure it with a ruler or tape measure.
Take a measuring tape and measure your wrist where you normally wear a bracelet. Add an appropriate length to the bracelet for a best fit. Please note the lengths below.