This is a 40 Needle / Tine 6.5mm Garter Bar: (20 needle version is available in this store) A garter bar is used on a knitting machine to remove the knitted fabric from the needles, turn it around, and replace the knitted fabric back on the needles. The ability to do this for an entire section of fabric (not just one needle) is necessary for garter stitches, and some lace patterns and cables. It can also be used if you have a need to temporarily remove a project from the machine. It fits 6.5mm machines. It can be purchased in sections of either 20 or 40 needles or tines. Purchase the number of sections as you need, depending on the number of needles in your typical project. Any number of sections can be used. The sections fit together and should be secured together using a piece of 1/4” threaded rod with nuts and washers on the ends. Threaded rod is inexpensive and can be purchased at a hardware store. The rod should be cut to the length of the assembled garter bars, with enough room to add a nut and washer at each end. Note that this just needs to hold them together for convenience, it doesn’t need to be tight. The material default for printing this is “White Polished”. Without the “Polished”, the surface of the material is slightly rough. If you find that your yarn still doesn’t slide easily on and off the garter bar, spray it with several coats of a glossy clear coat spray available at craft and hardware stores. This will help smooth the surface even more.