DAYTON, 1/2 in Compatible Shaft Dia, 1/4 in Shaft Extension Dia, Shaft Adapter Kit - 4X098|4X098 - Grainger
3mm Hexagonal Shaft Adapter for LEGO Wheels - Par | Hub's | PTR001232
92-A8110 : Motor Shaft Adapter, 3/16" Threaded to 1/4" Round | AMRE Supply
CNCTOPBAOS 8mm to 11mm Stepper Motor Shaft Sleeve 8x11mm Bore Adapter Turbine Reducer Shaft Sleeve for RV030 Worm Gear Speed Reduce RV30 NMRV030 Gearbox 0.31inch: Amazon.com: Industrial & Scientific
Amazon.com: 3Pack ShareGoo Metal 3.17mm to 5mm Shaft Adapter Change-Over Motor Axle Sleeve Compatible with Hobbywing HSP 540 550 EZRUN-3656 Motor RC Car Boat Plane : Toys & Games