A case adapted to be selectively connected to a first interface module, a second interface module and a third interface module is provided. The case includes a substrate. The substrate includes a first connection area and a second connection area. The first connection area is adjacent to the second connection area. The first connection area includes a first post. The second connection area includes a second post and a third post. In a first state, the first interface module is disposed in the first connection area. The second interface module is disposed in the second connection area. In a second state, the third interface module is disposed in the first connection area and the second connection area. The case is adapted to be selectively connected to different types of storage units.