This part holds the wires in the channel of a 20x20 aluminum extrusion. They are small and print quickly so you can print lots of them to keep all those wires organized. You might notice that the corners have little cut-outs. This is something i've adapted from an old typeface technique known as an ink trap. In printing, it is used to keep crisp edges in corners. The technique seems to work well for 3d printing. http://en.wikipedia.org/wiki/Ink_trapuse a .35 layer height or smaller in order to get enough infill. or experiment: it's not like you're wasting much plastic for a failed print!The Stl prints 2 clips at once.I use these on the Prism mendel.