RF module transmission distance is up to 500m.Offer byte- ... use protocol Features:1) RS-485 Mini power wireless RF module(500M)2) Nakedness and small size, suit for embedding3) ... from COM port, awaken from air6) Main APP: wireless meter-reading, order dishes system, queue system, corporeitytest equipment, electrical weighing ... 27 x 8mm (antenna not included) RS-485 wireless module, RS485RF transmitter