Xtenex produces the most comfortable, secure shoe laces on the market, providing the perfect fit for every extreme athletes and endurance sports starts to business men and children. Xtenex gives you "total-fit control" that is easy to adjust, but only changes when you want them to. Xtenex laces are ACCUFIT Compression Laces™ that feature enlarged (auto-blocking) knots that can be manually reduced in diameter size by stretching the lace apart where the reduction is needed, either for lacing or adjustment, release to set your compression preference. Knots create an adjustable compression zone between each set of eyelets to provide a tuned ergonomic fit. We currently have three different types of laces: The X-Series-- Our flagship lace. Designed specifically for endurance and extreme athletes, this lace has the most secure fit of all our laces. The XH-Series-- This is our hybrid lace. For those who aren't extreme athletes, but still do enough to need an extremely secure fit. Our XH-Series is easier to thread and adjust than our X-series, but still offers a secure and comfortable hold. The XF-Series-- Our flat lace. A lace that doesn't completely cover the eyelets, this series is designed for every day wear. By not covering the eyelids completely, it makes it easier to thread and adjust, while it's tapered design allows it to still keep the shape you set. This lace is perfect for every shoe.