Smoke alarm adapter plug that easily connects competitive alarms without rewiring. This product is compatible with BRK and Kidde 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 Kidde alarms: 125-series, 1275-series, 1285-series, 1276, PE120/PE120E, PI1200, JD135F.