Filament spool adapter for American Filament

American Filament is fantastic stuff made in my home town, but their filament spools have an unusual inner width that doesn't fit my spool holder well. This ring inserts into the spool to fill the gap, making the inner width the same as the outer, matching most other filament makers. 

The adapter is slightly smaller than the hole to provide a snug fit but remain easily removable. 

Outer diameter: 89mm

Inner diameter: 52mm

Depth: 17mm

Please comment if you find other brands of filament that use this sort of spool, and I'll update the tags or title.