Aico Ei146e Optical Smoke Alarm AC mains power supply and 9V alkaline battery back-up.

Fantastically useful to be able to slide of the old out of date alarm and slide on a new one.

Very easy to fit on the existing base

Works great, it came with battery and so pleased it slotted easily into old base

I telephoned Aico prior to purchase they were most helpful and although I was told could not purchase on Amazon obviously I did! It was to replace the older model so the good news is the base plate was the same so a 30 second job to install. tested been installed now for over 48hrs works a treat! Thank you Aico! 100% recommend.

I hadn't realised main-wired smoke alarms had an expiry date on a sticker attached to the outside of the alarm. Only when one malfunctioned did I spot it was 5 years beyond its lifespan. The smoke alarm detaches from the baseplate, there are instructions on it, but essentially push a screwdriver into a slot that is one side of the alarm to depress the catch then pull the alarm firmly across the ceiling in the same direction (you've probably already done this to replace the back-up battery at some stage). Apparently you're supposed to disconnect the alarm from the electics by flipping the relevant switch in the fuse box before doing this, but I only discovered this aferwards and it didn't sem to make any difference. You can keep the old baseplate attached to the ceiling, though so far as I can see you still have to buy the whole alarm with baseplate (which is why folks are trying to sell new baseplates on an auction site). The Ei146E smoke alarm fits the baseplate for the old Ei141 (and doubtless other models, but you'd need to Google), so it's just a case of sliding one out and sliding the other in. The Ei146 came with a Duracell battery included, so ignore Amazon's weird option of buying additional batteries. Also as these alarms come with an expiry date and they should be replaced every 10 years or so, it was good news to see the one I bought direct from Amazon has an expiry date of 10/2034, just under 11 years. Which you can't tell from looking at the box as it's a sticker on the alarm itself.