Good quality of plastics and assemblies. System preventing the closing without batteries. Although the notice is short, the interconnection of sensors is easily done by following some guidelines. Possibility to connect them all together or different group (if you have more than 2 like me). I confirm that they are compatible and RFXCOM triggerable remote (a good alarm signal). I can confirm the scope, but I have one per floor from the basement and they senchaînent up well under the eaves if the basement sounds (concrete slab on the ground floor, wood flooring for the rest). These are not the best for detection tests (prefer Chacon, also interconnectable) but the value at the time of my purchase seemed more than correct. Left to do my own tests, before the house burns.