... AFH tech,stable super anti-jamming capability cmmunication distance>300m digital doorbell now10 sets can be used as a group, person ... ,super anti-jamming.It can support 5 pairs(at least) communication at the same time without interuption.4. It can redesign ... function7. Power supply: AC 110/220V, Electric Current: within 200mA8. Communication distance: more then 500 meters in open land9. This doorbell ...