smoke is not mandatory, but gas leakage alarms must be installed, and 3C is required.

Gas alarms are roughly divided into three categories, imported, domestic two-wire system and domestic three-wire system.

the quality of imports is good, and the general price is also high, around 5111 yuan.

the domestic two-line products are the best of domestic brands, and the technology is the leading level in China.

the quality of domestic third-line cable is poor, and the price is low, so the accuracy of sensing sensitivity is poor.

from the perspective of cost performance, the domestic two-line Ogilvy is a good choice, and the domestic two-line is the first choice.