Every year the supplement European Conference of Postal and Telecommunications Administrations appears, which contains sheets of extra heavy paper (170 grs.) with plasticizer-free mounts.
Here you can store the stamps issued in the previous year.
On all sheets there are frames where you can put the stamps, usually with a picture of the stamp itself. On all these frames are transparent mounts to safely place your stamps in.
The Supplement Europe C.E.P.T. contains the year 2021.
The content consists of 13 pages; CEPT:483-495.