Hi William!
I know this thread is from a bit ago, but I spotted it and wanted to add Barnacle to your list in case you're still evaluating immobilization options. The Barnacle attaches at the windshield instead of the wheel, which makes it more visible, safer for staff, and quicker to deploy/remove. It also lets motorists pay to release the device themselves and return it-either to a nearby dropbox or directly to your office-thanks to a refundable deposit system.
http://barnacleparking.com
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Cara Ann Murwyn
Marketing Manager
Barnacle Parking Enforcement
Edison NJ
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