Plug In Doorbell - Safeguard Supply Dependable 3/4 Mile Long Range Wireless Unique 433MHz wireless door bell signal penetrates multiple floors walls even thick reinforced concrete, brick stone. USA Engineered Wireless Door Chime With Commercial Doorbell Features: Durable, ABS IP65 waterproof door bell button with green LED. No Limit On How Many Doorbell Chime Wireless Receivers You Can Add: Unlike other doorbell chimes, you can add as many receivers as necessary to provide the coverage you need as far as 4000' away. Expand By Adding Select Safeguard Supply ERA Products: outdoor motion sensor (ERA-DSTX), indoor motion sensor (ERA-PIR), door contact (ERA-UTX), portable receiver (ERA-VPRX), power receiver (ERA-DCRX).