Luminous Responsive Yoyo, yoyo balls glow K1-Plus come with regular flating bearing made by ABS, Style String Trick (1A, 3A, 5A), Durable and has high performance Keep The Noctilucent yoyo under the light or in the sunlight for a few minutes to charge the glow effect Heavier than before, and have more fun without weighting rings. A perfect toy for kids, friends, families, etc; Recommended for Kids Daily Practicing or Competition. If There is A String Get Stuck: 1.Remove the string firstly 2.Take a look at whether the ball is loose and the two hemispheres must be tightened well 3. Attach the string properly.(The most important thing) Applicable moves: (1A, 3A, 5A) Weight: 65g/set Diameter: 51.03mm Ball width: 41.01mm Shaft width: 4.38mm Bearing: 8-ball U-shaped shaft Screw: M4*16mm Colour:blue Material:ABS Package Contents: 4 * ball 4 * gloves 4 * velvet bag 20 * rope (random color, specified color not accepted)