Has anyone else received the CO400 with one 9 volt battery instead of the two AA batteries listed in description and on picture of packaging display?

Yes, Received the 9-Volt battery version. I live in California. I'm not a lawyer but my research shows that in California Smoke detectors and Combo Smoke/Carbon detectors must come with a 10 year lifespan battery. This law does not seem to apply to devices that only detect Carbon Monoxide like that one for sale here.

Why can't this be purchased in or shipped to California?

I live in California. Yes, I received the 9-Volt battery version. I'm not a lawyer but my research shows that in California Smoke detectors and Combo Smoke/Carbon detectors must come with a 10 year lifespan battery. This law does not seem to apply to devices that only detect Carbon Monoxide like that one for sale here.

the package picture shows 9-volt, but sounds like it is a crapshoot on what they will send you. which is better and lasts longer, 2AA or 1 9V? I hate taking out and putting in 9v batteries. so many to choose from. would prefer plug-in but would be too low.

I bought a package of AA batteries because this item description said it takes 2 AA. It does not. It takes (and comes with) one 9V. This is model CO400.

Red light is on. Is that normal? Tested and it chirps with test. Also checked battery.

YEs, red light is normal. If red light blinks - read manufacturer's guide in link below. https://www.brkelectronics.com/pdfs/2017/10/23/803bf30c.pdf

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Battery Carbon Monoxide Alarm | CO400

Product ID: 2536037

Details

Alarm
Audible
Brand
First Alert
Color
White
Global Trade Identification Number
Item Weight
11.2 ounces
Operating Humidity
10-95% RH

⚡Battery powered, works during power outages

📢85 dB loud alarm for instant alert

🔋5-year sensor life & replaceable 9V battery

158.94 DT

Duties & taxes included

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Sold byAmazon TunisiaDelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

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Description

🚨 Stay ahead of danger with the CO alarm that never sleeps!

EFFORTLESS SETUP - No installation needed—place it anywhere or use the optional wall mount.
TRUSTED LONGEVITY - 5-year sensor life backed by a 5-year limited warranty for peace of mind.
INSTANT LOUD ALERT - 85-decibel alarm cuts through noise to keep your family safe.
POWER OUTAGE PROOF - Battery operation ensures continuous protection even when the lights go out.
UNMATCHED ACCURACY - Electrochemical sensor detects CO with precision, wherever you place it.

The First Alert CO400 Battery Carbon Monoxide Alarm features a highly accurate electrochemical sensor with a 5-year lifespan, powered by a replaceable 9V battery to ensure continuous monitoring even during power failures. It emits a loud 85 dB alarm when dangerous CO levels are detected, requires no installation, and includes a 5-year limited warranty. UL listed and trusted by millions, it’s designed to protect your home and loved ones from invisible carbon monoxide threats.

Specifications

ASIN	B000N8OYXI
Alarm	Audible
Best Sellers Rank	#319 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #4 in Carbon Monoxide Detectors
Brand	First Alert
Built-In Media	Alarm; Mounting Bracket; User Manual; 9V Battery
Color	White
Customer Reviews	4.6 4.6 out of 5 stars (21,862)
Enclosure Material	Multi
Global Trade Identification Number	00029054000699
Item Dimensions D x W x H	1"D x 5"W x 3"H
Item Type Name	First Alert CO400FF Battery Powered Carbon Monoxide Alarm
Item Weight	11.2 ounces
Manufacturer	First Alert
Manufacturer Contact Information	1 (800) 323-9005.
Manufacturer Warranty Description	5 Year Limited Warranty
Mfr Part Number	CO400
Model Number	CO400
Number of Items	1
Operating Humidity	10-95% RH
Power Source	Battery Powered
Product Style	Battery Powered
Sensor Type	Electrochemical
UPC	029054000699
Unit Count	1 Count

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