Universal Filament Spool Holder with ball bearings. This will give you a very smooth feeding of your filament.
It is designed by myself, and it works like crazy. I like to watch the spool turning slowly and steadily.
You can mount ball bearings or not, two common sizes (16 and 22 mm) will fit.
NOTE: You can also mount these without any ball bearings, this is far better then just having the spool sitting on the sharp screw axes.