The very popular FireAngel ST-620 10 year optical smoke alarm was discontinued by the manufacturer in 2018. FireAngel have since designed an alarm that simply twist onto your existing base plate with no need to drill any more holes in your ceiling or redecorate. Suitable for BS 5839-6: 2019 Grade F1 domestic installations, this new FireAngel alarm features a Sleep Easy function which can silence low battery warnings for up to 8 hours and a large, central test / hush button for easy weekly testing – including a reduced volume feature to avoid startling occupants. It is the ideal solution to replace your old ST-620 with no need to change the base plate or redecorate.