'- Very reliable and easy to install driveway alarm- Transmitter operates on one 9-volt battery and has 25' of 3/8" diameter exterior hose that will lie across the drive- When a vehicle drives over the hose, a signal will be sent to the DCR-2500 receiver up to 1/2 miles away- Transmitter is weatherproof and meant for exterior locations- Up to 4 zones can be monitored with additional transmitters- Transmitters can be programmed so they will each sound a different tone at the receiver- Receiver: DK-DCR-2500DKDCRH2500