Three carbon monoxide alarms have been deemed a safety risk by Consumer Reports. 

The three alarms in question are:

• NetBoat WB_H3110061 LCD Portable Security Gas CO Carbon Poisoning Monitor (Amazon)
• Foho YJ-806 LCD Portable Carbon Monoxide Poisoning Monitor Alarm (Amazon)
• GoChange 882 LCD Portable Carbon Monoxide Poisoning Monitor Alarm (eBay)

You can read more about this from Consumer Reports at the following link.

http://www.consumerreports.org/carbon-monoxide-alarms/consumer-reports-rates-off-brand-carbon-monoxide-alarms-purchase/