What this heat pack can help:

• Improve blood circulation and digestive system.
• Help skins stay softer and healthier by stimulating the activities of skin cells.
• Relieve muscle aches and tensions of muscles and stress.

General applications:

• Arthritis
• Back pain, neck pain, shoulder pain
• Joint stiffness + Sprain
• Muscle Aches
• Chill or cramp in stomach
• Indigestion
• Beauty Massage  

How to use warm

• Apply heat about 3 minutes in microwave oven and uses.
• 10 minutes in boiling water to use.

How to use cold?

• 2~3 hours in refrigerator
• Half an hour in freezer to use

Caution!

• When you use hot or cold must use a pack wrapped in towels to prevent frostbite or burns.  

Microwaveable. Electrical heating not required. Completely portable.
The loess, windblown deposit of fine-grained silt or clay, inside this pack is rich in substances capable of emitting heat absorbed in the form of infrared (IR) energy.
Far-infrared (FIR) is simply a safe part of the spectrum of light emanating from the sun. Well, a 100 watt incandescent bulb produces about 85 watts of IR. Unlike ultraviolet light, FIR is harmless to the body.
FIR produces heat more efficiently because it matches your body's own emissions and penetrates even deeper into the skin.
Loess has enormous ability to contain heat for a long time.
The outside material of this pack is specially designed plastic that withstands intense heat.
The different texture of both sides allows the users to enjoy the intensity of the heat. 
This pack also can be used with normal electrical heating pad. User simply puts this pack underneath a normal electrical heating pad. It neutralizes the electrical field the electrical heating pad creates.

How heat therapy works [1]:
Heat application adds energy locally, and increase the metabolic rate of all types of cells. The local application of heat dilates the blood vessels and hence increases blood flow. Heat reduces muscle spasm by reducing tension in muscle trigger points [2], and it increases the ability of the muscle tendon unit to relax and stretch. The application of heat lowers the viscosity of collagen in these muscles, softening muscle and tendon, enabling muscles to extend more easily.[3] If the heat is applied over enough time, the muscle and tendons relax and stretch more readily. This is the mechanism that occurs when heat is applied to muscle cramps and also reduces painful stiffness in joints. Heat therefore reduces pain in a number of ways.

References:
[1] Meriyl, R. Business Briefing: U S Pharmacy Review. (2004).
[2] McCaffery, M. and Wolf, M. "Pain relief using cutaneous modalities, positioning and movement", Hospital Journal, 8, 1-2, 121-153 (1992).
[3] Melzack, R., Wall, P. D. "Pain mechanisms: a new theory", Science, 150, 971-979, (1965).