SR4U Glow in the Dark laces glow brightly when held under a bright light. The longer you charge them under the light the brighter they will glow. They are a direct replacement lace for all soccer/football boots including Magista Obra, Mercurial Superfly, Hypervenom Phantom, Tiempo Legend and all other soccer/football boots. The laces are 100% Polyester and are 47 inches or 119 cm in length.