They are also called "top-loading albums" in the United States, as the pages are inserted through the top of the protecting pockets.
For this type of album, it is the page protectors that are fixed with small screws. You slide then each page inside a pocket by choosing the place of the page.
You can then change very easily a page position without dissassembling the album, thus without removing screws.
You can also add transparent pockets in order to increase the number of pages of your album; to do this, you just need to unscrew the small mettalic screws, add the number of pockets needed and screw them back.
The protecting sheets sold separately exist in the form of books with 2 extension screws which are screwed onto the original screws for your album is closed without problem despite the addition of pages.

In each protecting pocket, you can put two pages back to back and even if the albums and spare pieces are sold with white or black sheets, you can use color paper or printed paper, ready to use or cut out to the format of your choice (for example, in the large sheet 50 x 65 cm).
The most commonly used format for this album is 12 x 12 " (measure in inches which is equivalent to about 30 x 30 cm), but other formats also exist, such as 8,5 x 11 " (measure in inches which is equivalent to about 21,6 x 27,9 cm, thus not exactly A4).
In France, this type of album is sometimes available in format 12 x 12 in some large supermarkets (Auchan, Carrefour, Leclerc) at a price rather reasonable which varies between 12 and 15 euros.
The spare pieces (5 protecting pockets + 5 white sheets + 2 extension screws) cost about 6 euros.
You can also order it through Internet.
And, if you don't like the cover page, don't hesitate to move your small fairy fingers to dress it with a beautiful tissue!

This model of album is may be the best compromise among all the albums that we have presented. It seems to have only advantages.