The particularly uneven, opaque stone finish is extremely durable and slip-resistant, providing consistency and a highly accurate stone-like texture. The wide opening (3.3 cm in diameter) allows for easy drinking and simple filling with ice. Sustainability is fun and safe: with a colorful, reusable water bottle made from certified materials that come into contact with food, we teach children how to care for our planet. The Kids Bottle does not retain or impart any flavors.