Update 2: it might also be compatible with Oculus Rift.
Update 1: now sold out!
The adapter will have a battery capacity of one and a half hours, but there’s a larger battery available with 5 hour capacity. The larger battery is designed to be kept in a pocket.
The price is 1499 yuan, or about US $220. Unfortunately, it already sold out within minutes of it becoming available. It also won’t ship outside of China.
Hopefully, they will make more stock available, and can make it available in other countries.