The manufacturer's production area includes many specialized workstations. Yarn for the mop head is cut to a specific length, sewn together by industrial weight sewing machine, and attached to the carrier substrate also by machine stitching. The substrates of molded plastic, vinyl, or heavy fabric are made to the manufacturer's specifications by outside suppliers. Assembly line workers pull frames from bins next to their workstations and fix them to the carrier substrates. Usually, the substrate is fitted to the frame, and the worker stitches it in place. While the substrate forms the general shape of the mop, the frame holds that shape rigid.