Yes, the Flex 2 PCIe 4.0 Bracket Kit Black is compatible with the Fractal Pop Air. It is explicitly mentioned in the list of compatible Fractal Design cases, which also includes Pop Air and Pop Silent. The bracket replaces 7 horizontal PCI slots and allows the graphics card to be mounted vertically, which ensures better air circulation. It is important that the case has "bridgeless" PCI slots, which is the case with the Pop Air.