Aaron - the HeadsUp System uses wireless technology but it's not RFID. To use it, just hang the alert sign in the garage, clip the InCar Alerter in the cab, and put the Gear Tag on the ROPS. Whenever you drive back towards the garage with the Alerter and Tag and get several car lengths away, the sign will flash and the Alerter will beep to remind you about the ROPS. We originally designed it to prevent a kayak or
bicycle roof rack crash, but reading this thread I'm pretty sure it would work for tractor ROPS too. - Karl (co-founder of HeadsUp Systems)