How to maintain the best battery operated smoke and carbon monoxide detector ？

SR-821THS is the best battery operated smoke and carbon monoxide detector uses internal dual sensors to detect carbon monoxide, smoke, and audible and visual alarms. It adopts independent installation and abandons complicated wiring. Keep your family safe. Then, how to maintain best battery operated smoke and carbon monoxide detector SR-821THS （Similar products are also applicable）？  The product […]