In all turntables a motor spins a metal disk at a constant speed. On top of the rotating disk (platter) is a mat and on top of the mat records are placed to be played. In the past rubber mats were used to hold the record in place so that it would not rotate independently of the platter. Nowadays slipmats are used to reduce the friction between the spinning platter and record, and is often made of a felt-like material. This way a DJ can scratch the record while the platter continues to spin underneath. In direct-drive turntables, the slipmat also helps isolate the record from motor vibrations that would be picked up by the stylus.