A really simple spool wedge that fits nicely on M8 rod that comes with the Anet A6 / A8 printer. Did a bit of research to try and find all the various inner diameter's of filament spool's and seems there isn't a standard size. Well, most seem to be around 50mm to 58mm but there are some as small as 25mm. Based on what I did find, this should hold any spool with an inner diameter between 25mm to 60mm.