Ei Carbon Monoxide Alarm Ei203EN And Smoke Alarm Ei100BWX. The Ei203EN Is A Carbon Monoxide (CO) Alarm Powered By 3 X AA Zinc Batteries (included). The EI100BWX Has An Easy To Use Test/Hush Button Allowing The User To Check That The Horn And Electronics Are Working And To Silence Nuisance Alarms (batteries Included).