The Ashford Jumbo Orifice Reducer insert goes into the orifice of your jumbo flyer. It makes the orifice hole smaller, which reduces the “chatter” of trying to spin fine yarns on a jumbo flyer.
Also available is the Bearing Reducer. This bearing goes in the front bearing of your spinning wheel, and reduces the size of the bearing so you can easily switch back to a regular flyer.
To help identify parts needed, you can find Ashford assembly manuals here: Ashford Assembly Guides