The answer — one pick, priced
Get the
Kidde Smart Smoke & CO
$5 under your budget
Smoke and CO in one hardwired unit for 42% less than the SC5 — 11 sources, no subscription, and the only alarm here that answers to both Alexa and Google.
Fit ledger — need → measured evidence
■ The catch — co-equal billing, always
It needs 120V wiring in the ceiling. This is a hardwired alarm with AA backup, not a battery unit — in a rental or an older home with no existing detector wiring you cannot fit it at all. And it will not interconnect with First Alert units on the same circuit; cross-brand interconnection does not exist.
Dealbreaker? Runner-up №1 is a sealed-battery unit that needs no wiring ↓
■ Every product has a catch. Verdicts that hide it are how bad buys happen.
Don't buy this if…
- you want basic non-smart smoke detectors without app connectivity
- you need commercial or industrial-grade fire detection systems
- you only need a CO detector without smoke detection
- you need whole-home professional fire monitoring with central station response
Wrong product for you is still a bad buy. These are the cases where we'd send you somewhere else.
Runners-up — if your needs differ
Adjacent verdicts — other needs, same method
Different budget, different household, different job — each of these is already researched, priced and verified. Take the one that matches your need.
Traps — this verdict avoids
Why the Kidde Smart Smoke & CO is right for you
It avoids every trap below — and for family of 4, under $80, it is the pick because it delivers:
The 10-year clock already started
A smoke alarm expires 10 years from the date of manufacture printed on the back — not from the day you installed it, so a unit that sat in a warehouse for two years gives you eight. CO sensors degrade on a 7-10 year clock whether or not they ever see gas.
An app alert is not interconnection
Only a hardwired third wire or a proprietary RF mesh makes every alarm in the house sound together. Wi-Fi and Matter push alerts reach your phone while the alarm outside your bedroom stays silent — and cross-brand interconnection does not exist at all.
Nest Protect is gone
Google discontinued the Nest Protect in March 2025. Existing units keep working to their 10-year expiry but cannot be bought new, and the First Alert SC5 is the official Google-partnered replacement — anything else you see listed is old stock or a reseller.
Provenance — 11 sources, dated
Winners are picked from the full research dossier at knowledgelib.io. Prices, stock and listings are re-verified monthly.