This add-on accessory will enable customers with smartphones and tablets to control temperatures remotely, access usage data and receive diagnostic notifications on all Navien products (NPE-2, NPN-U, NPN-E, NCB-H, NFC-H, NFB-H, NHB, NHB-H and NHW-A). Works with only one Navien unit via Wi-Fi connection. 3-year warranty from date of purchase.