  We have grown Cu$_2$OSeO$_3$ single crystals with an optimized chemical vapor
transport technique by using SeCl$_4$ as a transport agent. Our optimized
growth method allows to selectively produce large high quality single crystals.
The method is shown to consistently produce Cu$_2$OSeO$_3$ crystals of maximum
size 8 mm x 7 mm x 4 mm with a transport duration of around three weeks. We
found this method, with SeCl$_4$ as transport agent, more efficient and simple
compared to the commonly used growth techniques reported in literature with HCl
gas as transport agent. The Cu$_2$OSeO$_3$ crystals have very high quality and
the absolute structure are fully determined by simple single crystal x-ray
diffraction. We observed both type of crystals with left- and right-handed
chiralities. Our magnetization and ferromagnetic resonance data show the same
magnetic phase diagram as reported earlier.
