I've never used one, never plan on using one, and I usually cruise at less than 10mph over the speed limit. I'll still write something to the senator because this is just another BS law to pad law enforcement pocketbooks. Speeding tickets in general are BS- if a vehicle's speed down a road is so excessive that it puts people in danger, give the driver a reckless driving ticket. If it's within a reasonable range for the road given traffic conditions leave them alone. You'd think that the speed limit is set to a reasonable high value based on the design of the road and traffic flow through it, but usually it's just arbitrarily set 10-12 mph lower than the safe design speed of the road as determined by the traffic engineers who designed it because "slower is safer" in the minds of ignorant busybodies with their thumbs up their asses (our lawmakers).