This ozone generator puts out an actual max of 40 mins of 03 @ 1G/Hr (667mg 03 per 40 minute session) with a 30 minute shutoff/standby period probably to protect the consumer from excess inhalation. The unit automatically returns from the shutoff period to the 40 minute session and does this cycle continuously until the unit is shut off manually. For me, that was a good thing, because I habitually monitor my 03 output for various multitasking (room sterilization, mouthwash/perfume enhancements, vegetable washes, etc).
For the price, this is the best output of 03 in its price class (Under/Around $100) currently in 2012, and works great and is easy to learn how to use and manipulate.
Yeah, it's made in china, no detailed instructions, and doesn't have all the automatic safety shutoffs like other higher priced units, but does have a time regulator and outputs so much 03 that my sterilization efforts in my new residence was covered in days. This is a cheap, effective, must have generator for the road warrior, vagabond, or traveler/incoming resident that needs to change the quality of their residence.
Warned, the included porous air diffuser tips shouldn't be used in oil for long periods of time - oil will clog them up, and prevent 03 output in the tube with extended exposure to oil. Thus, just use the diffuser tips in water based solutions, and the hose itself un-tipped for oil solutions.