Aluminum Flex Shaft Coupler - 5mm to 10mm

Connect this to that with a set-screw coupler.
These couplers are made of machined aluminum and have a spiral cut that makes them slightly flexible so they can be fit to two shafts even if they are not perfectly co-linear and will help reduce binding effects. The way they're cut, they're a little springy in the X Y & Z linear axis but not in the rotational axis. That means that you won't get increased backlash - so they're suitable for precision CNC work.
This coupler will connect a 5mm diameter shaft to a 10mm diameter shaft. Comes with two sets of double set-screws (two per side) for secure attachment. You'll need a 2mm allen wrench to tighten/loosen the set-screws.
TECHNICAL DETAILS

Outer Diameter: 20mm / 0.8"
Inner Diameter (wide side): 10mm / 0.4"
Inner Diameter (small side): 5mm / 0.2"
15 grams