From the ManufacturerThe official equipment for Sports Stacking, the fast growing competitive sport for kids. Sport Stacking is easy to learn and addictively funProduct DescriptionSpeed Stacks is a highly addictive, competitive game that combines speed, action, dexterity and coordination. Play solo against the clock or head-to-head against friends. For an added challenge, turn off the lights and stack in the dark with this special glow-in-the-dark version. Super bright cups can glow for more than one hour at a time. Set includes 12 glow-in-the-dark Speed Stacks Competition Cups, an exclusive StackMat with glow-in-the-dark details and light-up timer, two glow-in-the-dark wristbands, sporty carry bag and full-color instructions.