2020 adjustable Corner joint for ERCF

Basically the extrusion I got had a square through it and I couldn't mount by normal means. It was nice quality, though, and I wanted to use it regardless. This allowed me to mount it onto my frame using hammer head nuts or spring nuts. Make sure to use washers everywhere, the model is a bit sloppy, but it will work. Works well with slightly shorter extrusion since you can adjust it.