LONG RANGE UP TO 900FT /300M - Either you are occupied in the garden or kitchen, you will always be easily informed when someone is calling from outside. FCC, RoHS certified.. 36 DIFFERENT RING TONES - There are 36 different ring tones with 5 levels of adjustable volume from 25db to 85db. IP44 WEATHERPROOF - Remote transmitter is acceptable for outdoor use. CE, FCC, ROHS CERTIFIED. EASY INSTALLATION - No batteries needed for the plug-in receiver. The push button can be fixed to the doorframe with the attached screws or double-sided adhesive tapes. EXPANDABLE & DIY - You can DIY to meet your requirement by pairing additional receivers and push buttons. 1 Receiver can pair up to 5 Push buttons, each push button can pair multiple receivers.