There are three sizes, the smallest size can be used as a keychain. Notice: 1. due to different measurement methods and tools, there may be an error of 1-3cm, which is normal. 2.  As the colors of different monitors are different, there will be some color difference in the product, please refer to the actual product received. 3. If you have any questions about the product, please contact us first, and we will give you a satisfactory answer.