Product name: Car smart luminous water coaster Coaster material: acrylic + LED Product size: diameter 68mm\2.68 inches / height 8.5mm\0.33 inches Installation location: water cup slot Color classification: colorful cycle (can switch blue, red, white, yellow, green, pink purple, ice blue monochrome) Instructions for use: The product is photosensitive and will light up when it is dark. It will automatically turn off in 15 seconds without vibration, otherwise it will turn off Battery power supply: USB charging is provided, and it can be used normally for about 15 days when fully charged. Features: This convenient and vibrant LED cup holder coaster adds a touch of fashion and function to your car. The accessory adopts an automatic color-changing design, which is perfect for enhancing the atmosphere of your car and adapting to your mood or personal style. Product includes: 2pcs car smart luminous water coaster Note: Please allow slight size errors (1~2 cm/0.39~0.78 inches) due to manual measurement, which is subject to the actual received; please allow slight errors in color under different monitors.