The J series is an older series in our product line that uses large, round gemstones rather than crushed ones. These gemstones produce a heated surface that presses into your muscles as you lie back on it to alleviate tensions and pressure. This is just like a hot stone therapy session that you can experience at a spa facility. Hot stones have a natural ability to relax muscles and tissue so that the user feels comfortable, more mobile, and relaxed. With a J mat, you can get this same spa experience in the comfort of your own home whenever you want. With this series of mats, silicone glue holds the gemstones firmly in place. This glue is durable and will hold the stones in place for decades, but it also causes the gemstones to reach a higher temperature than other mats, which in turn release a high concentration of far infrared rays and negative ions. The J series is available in most sizes including small, medium, full, and extra large. It is also available in some area-specific models such as a vest, belt, or pillow. All J products are heated models that provide far infrared and negative ion exposure, but there are no strictly jade models that provide more advanced natural therapies such as pulsed electromagnetic field therapy and photon light therapy.