Using two industrial-grade suction cups, the Barnacle mounts to a car's windshield, which unlike a boot, allows the car to be towed. The Barnacle comes with a screen to let the parking offender know why it was installed, and a credit card reader, so they can pay to have it removed. If the offender tries to drive off, an alarm will sound.
It's a definite improvement over the old Boot, but the people who made it clearly have never heard of the windshield-less Morgan 3 Wheeler. In addition, if an owner was motivated enough, they could just replace the windshield.
The Barnacle is certainly strange, but honestly, anything is better than getting booted.