This is a simple protective case for the FIIO RR11. The device can be slid into the case, but a certain thickness needs to be added inside, otherwise the case will be too tight and may scratch the device. I've attached some transparent tape to the inner wall to enhance the structural strength. It's recommended to use a support structure. Additionally, there are some bridging parts in the case, especially the bridging at the logo is slightly too wide. If no support is added, the external appearance may not be ideal.