> Both circuit breakers will only be activated once a day.

I'm not sure what this means, given that it already specified that either circuit breaker halts trading for the rest of the day...

"Both circuit breakers" refers to the 7% all-day halt circuit breaker and the 5% 30-minute halt circuit breaker introduced in the previous paragraph (which I omitted for brevity). A full quote would make more sense:

>The proposed mechanism will be tied to the benchmark CSI300 Index, which tracks the largest listed companies in Shanghai and Shenzhen, where a move of 5 percent in either direction from the index's previous close will trigger a 30-minute trade suspension across the country's equity indexes if the move occurs before 2.30 pm local time. After that, a 5 percent move will freeze trading until the market close at 3.00 pm.

>Meanwhile, a 7 percent rise or fall in the CSI300 Index will prompt a trading halt in the Shanghai and Shenzhen stock exchanges for the rest of the day, the statement posted on the exchange's website said. Both circuit breakers will only be activated once a day.

Didn't realize that--neat!