Notice: There are approximately 40 different boards in the packaging, some of which are not suitable for permanent markings, so some boards do not have numerical markings on them. But please don't worry about it, we provide detailed installation instruction that include photos of each board. You can easily distinguish it based on the photos. We also provide assembly videos to help you complete the assembly. Step 1: Before installation, please find an erasable marker and leave enough space to place these 40 boards in the room. Step 2: Distinguish each board based on the shape, hole posit