Before the advent of the compact disc, flexi discs were sometimes used as a means to include sound with printed material such as magazines and music instruction books. A flexi disc could be moulded with speech or music and bound into the text with a perforated seam, at very little cost and without any requirement for a hard binding. One problem with using the thinner vinyl was that the stylus's weight, combined with the flexi disc's low mass, would sometimes cause the disc to stop spinning on the turntable and become held in place by the stylus. For this reason, most flexi discs had a spot on the face of the disc for a coin, or other small, flat, weighted object to increase the friction with the turntable surface and enforce consistent rotation. If the turntable's surface is not completely flat, it is recommended that the flexi disc be placed on top of a full sized record.