XTENEX Accu-Fit Adjustable Compression Laces are the ultimate shoelace you don’t have to tie. Xtenex Xlaces feature enlarged (auto-blocking) knots that can be reduced in size by stretching the lace apart, either for lacing or adjusting. Release the tension back to the lace and the knots will reappear to set your fit. Knots create an adjustable compression zone between each set of eyelets to provide a fine tuned ergonomic fit. Your shoes have never been this comfortable.