O
Octopus
The FB 'Muppets' are not allowed to take old ones down even with the verbal permission of the home owner. FB 'Muppets are supplied with smoke detectors to put up, they can't recommend hardwired ones or any make. They may be Muppets in your eyes then hopefully your never need to be carried out of a burning building by one of these Muppets.
My point is that they leave faulty smoke alarms in properties, well past there dates as on the labels visible on the side.
They either do it right or not at all IMHO.