Smoke Detector recommendations

I started buying Halo’s for my house after 2 relized the cost was going to too much. Then I found this:

The Halos are still connected and work great for the rest I followed this write up. The Halos do not interconnect with the rest of the house but they are close enough to the interconnected ones that if they trip the interconnected ones will be going off also. If I had seen this write up first I wouldn’t have bought the Halos at all