It sounds like two of the sides should be able to be moved to cover the paper -- the other two sides are covered by the non-movable sides.

An example of a two-bladed easel:

http://www.bhphotovideo.com/c/produc...Enlarging.html

There are 4-bladed easels that all four sides are movable:

http://www.freestylephoto.biz/8501-B...ng-Easel-11x14