The First Alert L1 is a battery-powered sensor that ... and the bottom holds a pair of water sensors and a removable cover for the battery compartment. The status LED flashes orange to warn ...

Note that the battery-powered model (reviewed here) is powered not by standard AAs but rather by a three-cell lithium power pack. First Alert says this battery is rated to last five years ...

But us here at Techlicious have been really impressed with the First Alert Onelink ... A 10-year battery, good for the life of the unit, powers the Smart Alert detector. (FEMA recommends you ...