Polyethylene gel bladders, with the option of alternating hot or cold application. \ \ hot application: \ indicated for back pain, stiff neck, rheumatism, hypothermia and whenever a hot bladder application is required. \ the bladder can be converted to hot in two ways. \ a) by immersing in hot water for about a minute (at 80 degrees Celsius maximum). \ b) by placing the bladder in a microwave oven for a period of 25 seconds at 600 watts. the gel is evenly distributed in the bag. \ to place the hot bladder, it must first be wiped after being immersed in hot water and then wrapped in the special case included in the package before being placed on the skin (this applies to both cases of immersion or microwave preparation). \ \ cold application: \ indicated for hematomas, sprains, injuries and in general where cryotherapy is recommended. \ the bladder can be turned into a cold one by placing it in the freezer for approximately 1 hour. \ to place the cold bladder, it must first be wrapped in a case or cloth before being placed on the skin. \ \ dimensions: 13.5cm x 18cm \