16pcs Saw Blade Bushing Set Saw Blade Adapter Ring, Angle grinder inner aperture conversion gasket,1 Inch to 20 mm, 1 Inch to 5/8 Inch, 7/8 Inch to 5/8 Inch, 20 mmto 5/8 Inch,4 per Model - - Amazon.com
QiNiuTools Saw Blade Bushing, Adapter for Circular Saw Blades, Saw Reducing Rings, Washers, Spacers, Pack of 5 (20mm x 16mm) - - Amazon.com