The Xtenex Elastic Shoe Laces introduce the patented inde Xed-TENsioning-n E Xus elastic lace technology that creates adjustable tensioning between shoe eyelets. This technology addresses the lace migration issue which is the source of footwear associated pain & discomfort. The 75cm long Xtenex laces have an elastic core & a series of knots along the lace at consistent intervals. Leaving more knots between eyelets will produce a looser fit while less knots will produce a tighter fit. The knots disappear when the lace is stretched, allowing to thread the lace through the eyelets. Releasing the tension makes the knot to reappear.