Heat and fire protective items

A method, comprising:

• shaping a first-shaped transformable fiber at a first crystal structure from a pre-determined configuration into a new shaped configuration to provide a second-shaped transformable fiber, wherein the predetermined configuration and the new shaped configuration comprise two arrangements of a snap-ring configuration;
• inserting the second-shaped transformable fiber into a cavity of a heat and fire protective item;
• heating the second-shaped transformable fiber above its transformation temperature to a second crystal structure to transform the new shaped configuration to the pre-determined configuration, wherein the pre-determined configuration forms an air pocket within the heat and fire protective item;
• and
• cooling the first-shaped transformable fiber below its transformation temperature to revert the transformable fiber back to the new shaped configuration at the first crystal structure.