Made of plastic, this set features connectors with standard size threading. Each pack includes 20 connectors in 5 colors: 4 red, 4 blue, 4 yellow, 4 green, and 4 purple. The connectors have a striped surface for easier gripping and rotation, allowing repeated use. This is an engaging educational tool that helps children explore basic scientific principles related to air, water, physics, motion, and energy. To create a vortex, connect a bottle filled two-thirds with water to an empty bottle using the connector, then shake vigorously three to five times—the swirling tornado effect will appear instantly. A fun and interactive science activity for kids, ideal for learning at home or in the classroom. Great as a gift for holidays, birthdays, or special occasions. Package includes: 20 x Cyclone Tube connectors (4 in each color) Specifications: Material: Plastic Length: approx. 4.8 cm (1.88 inches) Outer diameter: approx. 3.2 cm (1.27 inches) Inner diameter: approx. 2.9 cm (1.13 inches) Weight: 20g per piece