Offer is valid for existing residential customers only. Offer does not apply to pre-existing agreements for monitored smoke detectors. Purchase of one Monitored Smoke Detector required for free Smoke Detector. Limit of one free Monitored Smoke Detector per customer. Minimum monitoring agreement required on Monitored Smoke Detectors. May not be combined with other offers. Certain restrictions may apply. Offer valid through 03/31/17.