Knit fabrics can be made on more than one set of needles. Unlike single knit fabrics, double knit fabrics are produced from two sets of needles. You've seen how circular machines can be used to produce single knits, but they can also be set up to create double knits. To accomplish this, a second set of needles is arranged in a dial above the cylinder. This dial has slots that hold the needles at a right angle to the vertical cylinder needles. This illustration shows you how a circular knit machine has tricks in two places. In the cylinder below, and the circular dial, just above. The dial has grooves cut in the outer perimeter in the same cut or gauge as the cylinder. Another view shows that the needles in the dial rest horizontally in their grooves. Also, there is a precise gap between the cylinder and dial. This distance is referred to as dial height. The dial height is important because it directly affects the stitch length, which controls physical parameters such as weight, width, thickness, strength, and hand. When double knit fabrics are produced, the knitting cycles of knit, tuck, and float are the same for the dial as they are for the cylinder. The needles in both the dial and cylinder have butts and are cam activated. Because two sets of needles are used, sinkers are not needed. As the yarns are knit and the fabric is formed, the tubular goods are removed to the inside of the cylinder, as with single knits. Another type of weft knitting machine, designed to make single and double knit fabrics, is a flat bed machine. These machines may have the two needle beds in the same plane, but usually they are set up in a V configuration and then referred to as V bed machines. These knitting machines are used to produce tubular fabrics or flat panels that can be put together to form a garment. Because the width within a panel can be made to vary, this system minimizes waist and sewing. Also the technology has matured so that a complete garment can be made on this machine. Here's how V bed machines create the loops required to produce a double knit fabric. First, loops are at rest. Then both loops clear the latch. New yarn is received and both loops are cast off as new stitches form. You may notice that these actions result in a fabric that is structured differently than a single knit. You've seen how weft knit fabrics can be made on either circular or V bed machines, with one or two sets of needles. Remember when it's two sets of needles, we define it as double knit.