My home isn’t that old, but the builder-installed smoke/CO detectors started failing. I am not talking about the lame single beeps (always in the middle of the night) that announce that it is time to change the backup battery. No, indeed…the old units made the triple-beep that said they needed replacing. Of course, they chose the middle of the night to fail and no less than three of them failed at once.This package of three is perfect for my needs. These are a direct, snap-in replacement for the originals — I did not have to change around the plugs or the mount. It was plug in, mount to the ring, and twist to lock. Probably the easiest home DIY project I have had in a while.Pay the extra few dollars, get the direct replacements, save yourself the headaches.