Hello, Quick installation. Loud alarm. Very little earlier than the others. Go unnoticed. Factories in Denmark. NF. The DDF is stored in the list of standard DDF NF292 listed by AFNOR. PDF available online. They they have to be screwed to comply with the NF and not sotchés. Check with your insurer. Contrary to some reviews I can not go to their website bp and save my two smoky. http://www.smoky-nano.com/