Sports socks, like all socks, require elastic fibers to fit snugly on the feet. Therefore, almost all socks contain elastic fiber, and it is rare to find socks that are 100% cotton. For most ordinary and many sports socks, spandex is used as the elastic skeleton. High-quality spandex has suitable elasticity and good air permeability. The elastic life of spandex can last at least 6 months to 1 year. However, stock socks, which are sold online at very low prices, are often stored for too long in inappropriate conditions, causing the spandex to lose its function. Inferior spandex can also lose its wrapping power quickly. Therefore, consumers should be cautious when buying low-priced sports socks online, as the wrapping force cannot be determined through pictures. Although adding elastic can increase the difficulty and cost of hosiery weaving, most socks have at least one circle of elastic at the sock opening or the arch of the foot for reinforcement.
Sock seams are sewn using specialized seaming machines, which are fast, efficient, and inexpensive. However, machine-sewn heads lack comfort, especially in thicker socks, where they can create a hard bulge above the toes. High-end sports socks use handmade boneless seams for greater comfort. Manual operation is required, and the operator must have high precision to avoid leaks in the seam. Boneless seams are lower than the thickness of the sock and have no seams or corrugated lines, making them much more comfortable. Non-high-end socks generally do not use boneless seams due to a higher defective rate, despite the higher costs and quality inspections required for this process.