The material structure of the underwear consists of inner and outer fabrics and intermediate composite layers. The middle composite layer is the key to thermal underwear. Initially, the underwear composite layer used agricultural film technology to create the warming effect, which is difficult to achieve with ordinary fiber materials, using the superior heat and wind resistance of plastic films. Using needle punching technology, make a certain number of small holes in the film, mix some fibers on both sides of the film, then glue this composite layer to the inner and outer knitted fabric with glue, Of material that forms thermal underwear. Currently, the materials for underwear are generally changed to ultra-fine fibers, hollow fibers, special chemical fibers such as far-infrared fibers. Since these fibers have low thermal conductivity, they have excellent heat insulation properties. Steps/Methods First point when choosing thermal underwear: Intuitive visual first impression of quality product is pure color, stylish appearance, clean wireless head regardless of shape or color , A uniform cloth surface. Also, keep in mind that the label is neat and that the handwriting is clear.Some counterfeit manufacturers can achieve discreet points with their clothing processing techniques, but the label easily leaks feet. is. By smelling, scents are an important basis for animals to judge things. For example, humans inherit this characteristic. Good underwear has a more natural odor, with a slight odor of dyed material, poor underwear has a strong odor and thorns. The smell of nose and the smell of organic oil. The feel is an important criterion for observing the quality of underwear. The first is touching the thickness, the overall thickness is uniform, there is unevenness, the surface fabric is comfortable, the seams are smooth, horizontal, vertical, wrinkle, tactile, soft and flexible, elastic Excellent, feel the fabric density, whether the clothes are drawn, the underwear material is generally gorgeous, mainly cashmere, whether the hands are smooth and soft to the touch, bright colors, open palms upwards in the opposite direction Touch to clearly see the stuffed lining, whether the stuffed animals are evenly placed, and whether there is hair loss. Then touch the plush toy again to see if it returns to its original state. Underwear with poor craftsmanship and materials is easily deformed, and it is not possible to return the deformed underwear to its original shape. You can also pinch and pull for analysis. Good quality underwear can be pulled back to its original shape by freely pulling the cuffs, neckline and hem. Part of clothes. Wear it for the most intuitive experience. There is no swelling when worn, the joints move freely, and there is no irritation to the skin. After taking it off, it immediately returns to its original shape. Long sleeves, short clothes, no left-right asymmetry issues.