USAReplacementparts Crank Shaft Adapter Taper to 1'' Inch Generator Pressure Washer Engine Bushing Made in The USA: Amazon.com: Tools & Home Improvement
Pololu - 12mm Hex Wheel Adapter for 6mm Shaft (2-Pack)
Amazon.com: Hobbypark 1/8 inch 3.175mm to 5mm Pinion Adapter Shaft Adapter Reducer Sleeve Motor Axle Change-Over for RC 540 3650 Brushed / Brushless Motors (3-Pack) : Toys & Games