There are two types of aluminum picture frames. The "backloaders" are higher than the normal aluminum picture frames. The back wall can also be removed here in order to attach the picture directly to the back wall.
You want to give your Pixelhobby picture the right frame, then you will find a large selection of different sizes here.
To find your way around:
You can find the number of base plates and the dimensions of the picture directly with each set. The panel arrangement (P = Portrait; L = Landscape) is on the bill of materials.
You can see how to frame your picture here: (English video)