The item will detect both smoke and carbon monoxide. I owned on previously and it lasted for almost seven years, I like that it talks to you to tell you what is wrong with it. like low battery or smoke or carbon monoxide.
I have received the toner but there were no directions with the product to inform as to how much put in the cartridge. I have seem smaller bottles on the market where you add the entire bottle. This bottle looks like it could be two or three cartridges. I am investigating the amount of toner needed for a refill. Until I get that information, the bottle will stay on a shelf, unused.