Bosch Professional Reduction Ring for Circular Saw Blades (Reduction from 15 to 12.7 mm, thickness 0.55 mm, accessories for circular saws) - - Amazon.com
Gunpla 4-1/2-inch 40 Tooth Alloy Steel TCT General Purpose Hard & Soft Wood Cutting Saw Blade with 7/8-inch Arbor(Reduce Ring 5/8 inch) - - Amazon.com
Reduction Ring for Circular Saw Blade - Bosch Professional