We've all seen them … illegally-parked cars that have had wheel boots placed on them, which won't be removed until the fine is paid. Those boots are heavy and cumbersome to carry, however, plus the people who put them on typically have to kneel dangerously close to passing traffic. That's why New York-based Ideas That Stick developed the windshield-blocking Barnacle.
Folding in half when not in use, the Barnacle adheres to the windshield using two pump-activated commercial grade suction cups that can reportedly withstand hundreds of pounds of pulling force. Parking officials can carry several of the devices in the back of their vehicle, and need only lean across offending cars from the curb in order to install them.
Should the drivers of those cars try removing the Barnacle on their own or driving away with it still on, a built-in alarm will sound (that said, one has to wonder how many people might just drive it away with it on anyway).
Instead, once they've paid their fine over the phone, drivers will be given a numerical release code for the Barnacle on their car. After punching that code into the integrated keypad, the suction cups will release and the device will come off. They then have 24 hours in which to return it to a drop-off location – if they don't, presumably they'll be fined once again.
Additionally, in instances where parking fines remain unpaid, cars can be towed with the Barnacle still in place. With wheel boots, the device has to be removed before the car can be towed.
Source: Ideas That Stick via Laughing Squid
Boot seems way more effective IMO.