Cup Holder: The expandable base can be adjusted from 2.6 to 3.8 inches in diameter to fit different types of car cup holders. Simply twist the adapter's base to extend or retract the base, and it can be firmly fixed in the car's cup holder. U-shaped notch: This design is very practical as cups or mugs with handles can be perfectly placed in this car cup holder without tipping or spilling. Shrapnel and silicone coaster: The silicone insert in the car cup holder allows cups to be easily inserted and removed from the adapter. The coaster ensures that the cup stays firmly in the cup holder when driving, it will not shake or fall out, and prevents friction against the bottle body. Durable material: The main body of the car cup holder is made of plastic (ABS), lightweight, durable, waterproof, and easy to clean. Suitable for various sizes: The silicone shrapnel allows the adapter to work with bottles/mugs with a diameter of 2.9 to 3.8 inches. Extended version of the cup body to fit taller and larger mugs, more stable and less prone to shaking, and fits most water bottles from 20 oz to 40 oz.