The printing process used to print How Stuff Works Express is called web offset lithography. The paper is fed through the press as one continuous stream pulled from rolls of paper. Each roll can weigh as much as 4000 us dollar(1 ton). The paper is cut to size after printing. Offset lithography can also be done with pre-cut paper in sheetfed presses. Web presses print at very high speeds and use very large sheets of paper. Press speeds can reach up to 50,000 impressions per hour. An impression is equal to one full press sheet (38 inches x 22 and three-fourths inches), which is 12 pages of How Stuff Works Express.