Article moveable between two positions and a method of combining two or more of the same

An article is moveable between a first position and a second position and biased to the second position. The article is retained in the first position by retaining means until a predetermined condition is met and when met, the biasing means are released to move the article from the first position to the second position. The predetermined condition is met when at least one formation of a plurality of formations located with respect to at least one face of the article is moved from a first position to a second position, thereby releasing the retaining means. The article further includes user selection means to allow the user to select which one, or combination, of the plurality of formations, when moved, will cause the release of the retaining means.