â Adopts refined 2 dual PIR sensors, intelligent digital chip. â Advanced “true motion recognition and pet immunity” technology to avoid interference. â Remarkable pet-immunity function to prevent pets under 25 kg. â Germany imported optical filter to block motley light up to 99%. â special lens anti UV to reduce false alarm at maximum. â Automatic memory of environment change to avoid false alarm triggered by hot/cold air current or operation machines. â Super filter can be used outdoor to avoid interference that other detector cant avoid. â Fully sealed design, two-layer water proof, macromolecule film plating for indoor and outdoor installation.