I have two of these for my double axle travel trailer. I used them the first time in my driveway and they worked great. I used them on my next trip with the same result however after returning home they wouldn't work anymore. While it was sitting in my driveway I put tire shine on the tires after washing my trailer--BIG MISTAKE---now they just shoot out from under the trailer, even after hammering them in a little.
I just got back from my first trip of the season and tried again. After the entire winter, the driveway still will not hold them. I even scratched both sides up to try and provide more friction. No luck. They might work out on my next trip but they don't work in my driveway.
One can always apply some "Grip Tape", like the stuff used on skate boards, stairs etc., peel and stick it on the entire leveler surface. Simple fix for what looks like a great product.