A polyisocyanate-based elastomer having a ratio of the storage modulus at 20\xb0 C. The method consists of purchasing the test kit, placing the test kit on a device that produces air circulation and blowing air through the test kit. The heat pipe unit is received in the receiving space and is disposed on the open casing. Posted barter orders whose first class of items match the second class of items of a barterer’s order are preferably displayed.