How far does it reach?

The magnetic field drops off very quickly, so the energy doesn't transfer across a room or anything like that.

However, when it's close to your body it's resonating with the water in your body and the electrical conductivity of your body. Think of it like a pebble in a pond.

The energy is delivered where the device is at, but that pebble makes a wave that travels through the water in your body. That's how it can be in your pocket and the energy still reaches your foot.

Plus the alternating magnetic wave makes an electrical current, a very slight one albeit, and the energy can travel throughout the entire body due to the electrical conductivity of skin, organs, etc.