Greatly reduces the dreaded "tower shake" when doing honeycomb and some other infill at high speeds. Noticeably improves the rigidity of the Kossel 2020 design. Also, this is a good upgrade if you are transporting your Kossel a lot. It will help ensure that the extrusions don't slip if the machine gets jarred. I tried smaller braces that fit up tight against the vertex brackets, and they seemed to do almost nothing. These actually work. I noticed an definite improvement in the surface quality of my printed parts after I installed these. Created in DesignSpark Mechanical.The carbon fiber box tubing can be purchased from HobbyKing. 300mm length: http://www.hobbyking.com/hobbyking/store/__55336__Carbon_Fiber_Square_Tube_10_x_10_x_300mm_US_Warehouse_.html 250mm length: http://www.hobbyking.com/hobbyking/store/__55335__Carbon_Fiber_Square_Tube_10_x_10_x_250mm_US_Warehouse_.html The 250mm length is adequate if you are using 300mm horizontal extrusions. My Kossel uses 350mm horizontals and I had to go with the 300mm box tubing. You must accurately determine the proper length of the CF tubing before final assembly. Do a trial fit of the parts and tubing in order to determine that length. The upper ends should almost meet when the are the correct length. (see transparent view of center brace to get an idea of how close they should be) Use 16mm long M3 capscrews to secure the box tuning into the braces. Make sure they are bottomed out. Mark with masking tape before final assembly if your tubes are tight and your are not sure if they are bottoming. The braces attach to the extrusions with 8mm M3 capscrews and T-nuts. I suggest printing in ABS for flexibility. It makes assembly easier. There should be adequate clearance between the corner braces and the capscrews securing your ball joint rods to your carriages (unless you are using a weird carriage that is wider than usual) The tolerances are fairly tight to match my printer. I suggest printing out one set first and testing the fit of the CF box tubing. Scale up the part by 0.5% or so if you really need to. It all goes together quite easily if you do things in the right order. If you need help, leave a comment. No chopping, hacking, or butchering with netfab or meshmixer, etc please. If you want something changed, please ask. Thank you.