This incredible piece of equipment is fully electronic and turns a purl stitch into a knit stitch allowing you to create wonderful patterns using the same yarn. It operated on a standard gauge single bed punch card or electronic machine. Using a pattern the carriage recognises the un-punched holes and transfers the stitch from purl to knit. The carriage can be used from beginning to end by casting on and doing ribs as well as knitting the main body of the garment. It operates over the full needle bed and has two speeds, 0.6 and 0.8 seconds per stitch which is not speedy but you can leave the carriage to chug away while you get on with something else. Different models work on different machines.