Genuine Lenovo D Cover Assembly for the ThinkPad X13 Yoga Gen 1. This component is the bottom base cover, also known as the lower case or D-Cover ASM, with part number 5CB0Y87521. It is specifically designed for ThinkPad X13 Yoga Gen 1 20SX and 20SY models, ensuring proper fit and structural integrity for this 13.3-inch convertible laptop. The component is identified as black BK BBB2 and serves as a replacement part for the chassis on the lower side of the device. Usually, no additional accessories are included beyond this cover.