I've had a Dakota Alert for 10 years.  I started with the rubber hose laid out in the driveway that tripped the alarm, then graduated to a buried sensor which works much better.  Either way, I've been very happy with mine and with the service from Dakota Alert.  When I bought the second transmitter for the new buried sensor, my receiver in the shop didn't work (I have receivers in the shop and house).  I called and they had me send the transmitter in for an "adjustment", no charge, they paid the return shipping, and it's worked fine ever since.

HTH,

Mike