The First Alert ADF-12 Smoke Alarm Adapter Plug 12pk easily connects competitive alarms without rewiring. This product is compatible with BRK and Firex Smoke Alarms and saves time and installation costs when retrofitting existing homes or apartments. Compatible BRK alarms: 4120-series, 9120-series, 7010-series, 5919,2002RAC, SC6120B, SC9120B, HD6135FB, RM3. Compatible Firex alarms: 406 (G-6), 4518 (ADC), 4618 (FADC), 484 (PG-40), 4480 (PAD), 5700 (ADH), 499. First Alert designs and creates safety products that preserve and protect the things that are the most important to you, from your children and family to your home and the priceless memories stored inside.