Simple installation,you will enjoy smooth and quiet movement,without making a harsh sound. Range of use: wheels are suitable for different types of storage boxes, making it easier to move. Material: plastic Quantity: 4pcs/set Color: blue/pink Size: as the picture show Package List: 4pcs/set * Mini Caster Notice: Due to the light and screen difference, the items color may be slightly different from the pictures. Please allow some differences due to manual measurement. Thank you for your kindly understanding.