It has an external 2 dBi antenna and can better receive wifi signals. It can support up to 3 garage doors at the same time. (2 doors sensor is included in the package. the third door sensor need to be purchased separately)No monthly fee or any other subscription fee! Please check whether your garage door model is in the compatibility list in "Product guides and documents-User Guide". If your garage door needs accessories to solve compatibility issues. It comes with a high sensitivity sensor which monitors the status of garage door more accurate and the signal stays stable. And you can check the garage door open/ close operation records through the APP. Stay alert by different notification modes such as garage door open/ close status, overtime notification and overnight notification to remind you close the garage door. You can control your devices hands free, just give voice commands to turn on/off the connected devices. Please scroll down and check in the "Product guides and documents - User Manual"for more product information. Installation is much easier than you may think. Pls make sure your wifi strength is acceptable near your garage door. Note: 2.4 GHz Wi-Fi network support only.