Tiny (around 1 thumb high) alarm, this was installed for a while, but still works on test, instructions included. I think once the battery runs out it would need replacing, but as it's a simple install and not needing connecting to mains it could really help for safety if you don't have one.
May be able to deliver if it's on one of my usual routes and you don't have a deadline.
Tiny smoke alarm, easy to install (Buggs Bottom RG4)
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