FIRST ALERT / BRK ALARMS BRK 9120B (OLD# 4120B) 120V AC/DC SMOKE DETECTORLot of 12

Folks, this is the way to replace you BRK Alarm especially if you had old one like me. You go to the site with model number from old one and the site information will tell you if obsolete and the new model number to order. Also you can with this model get a gas detector (Carbon) also. So I order one for downstair and the rest were order through a batch of 12. So, in 5 years I can replace the new ones already having the kit. I didn't have to change the wires. However important in replacing by twist off and disconnect the wire prongs first. Then with screw driver I 1/2 twist the screw enough just to twist off the old base ring off. Then replace with new one. Be sure to connect the two prongs into their correct hole and the single into its slot. That it except pulling the tape out from the battery area to activate the new smoke fire alarm. My local fire station told me if I needed help on anything to stop buy and they would gladly talk me through the process. But it was so simple for me that I didn't have to contact them.

New replacements for 4120B that were 15 years old. These were a direct replacement. Used the new base mount that fit exactly the same as the old base mounts that had yellowed over time. Was able to sue same electrical connection. Replaced 12 smoke detectors in about 30 minutes.These were ordered as a 12-pack and came well packaged in one box. Quick delivery as well. Would buy from seller again.

Replacement for 10+ year old smoke detectors in my house. Easy easy. They come with batteries and wiring connectors. I didn’t have to use the connectors because I was replacing the same thing.

Smoke detectors were easy to install and also came with batteries included, which was great! Would recommend purchasing these smoke detectors. As the original First Alert Smoke Detectors were installed in 2004, so just having install these 14 years later - I say a great product!

They are great for the money, I ordered more than I needed so I am just giving them to my children,

Good replacement for a good price. I used them to replace my Firex alarms. I had to remove the old mounts and connectors then install the new mounts and rewire the new connectors. It was easier then installing a ceiling fan or light switch.

Very good product

Nicely packaged and easy to install