This is a pretty simple part I made to extend the 2020 extrusion used on the top of my sE1X(http://mobious.org). I needed this part or else I would have had to order a new 2020 extrusion.You need 4 t-slot nuts (5mm) for this part and 4 M5-10's. I simply cut the extrusion in half and placed this in the center..it is two parts so slide both on one side, then slide the extrusion in the opp. end and done. Enjoy! -papabur