I have a Nighthawk Carbon Monoxide alarm that started acting funny, The led display which normally reads zero, kept dropping out and not reading anything, except for the tiny flashing dot, that says it's working. I went through the manual and this issue isn't discussed, so I called customer service. We went through some reset procedures and he couldn't figure out the problem. He says the unit is 6 yrs old but they have a life expectancy of 7 years, so I'm sending you a new one! Wow! The unit manufacturer is Kidde and they are $30 on Amazon. They also make smoke alarms, fire extinguishers, escape ladders. If only all customer service was like that. Just wanted to share a great customer service story. I know if I ever need home fire safety products in the future, I'm looking at products from Kidde first.