travel by green sticker vehicles has always been illegal on these roads. remove the plunger portion of the device and place the end with the pad on the surface to be tested. in the mean time, i hope i was able to show you how fun and easy using a system like this can be. i received my free copy today and am very pleased with it. as they say, time will tell. check out our back issues page to find out what you can still get your paws on. then the artificial sand is the first choice. 