SINGER 400W4 is a double rotary disc take-up, high speed, single needle, lock stitch, drop feed machine for stitching upper and lower cord on tape. It is also suitable for application of slide fastener units.

The machine comes with a 7/16 in. diameter, 32-1/2 in. length driving belt and a 4-1/4 in. diameter driving pulley. It has a balance wheel with a 5.9 in. outside diameter for a 3/8 in. "V" belt and a 1 in. bottom diameter for a round belt. The machine has a presser foot for size 12 and 15 cord, a tape guide, a rotating hook, and a tape tension complete with various components.