For 6mm Ornithopter gearbox, micro outrunner brushless motor OP03X 20000KV, with 6mm cylindrical fixed base, For 1S (3.7V) Lipo Battery, Shaft 1.0mm,  max current 2.5A

Bottom

Size

Top, the root of the motor lead is no way to fixed with glue

With M0.3 coper 7T pinion

For 6mm Ornithopter gearbox

Weight about 2.97g