48-strand polyester ropes, perfectly round, very flexible, and compact. The new ropes guarantee greater control and last much longer than the previous version and are available in both 6mm and 10mm diameters. The colors are extremely vibrant, and the phosphorescent version (GLOW IN THE DARK) lights up impressively in the dark when charged with a sufficiently powerful light source. All fluorescent colors (yellow, orange, green, and fuchsia) but especially the phosphorescent one are incredibly bright when used under a UV light source.