The xtenex elastic shoe laces introduce the patented indexed tensioning nexus 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 and discomfort the 75cm long xtenex laces have an elastic core and 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