We bought these to run a power cord through that lays on our driveway. We tear the cord up with car tires every year (cord runs heater tape on our pool main over the winter). So far, we have no issue with cracking or breakdown of the units. If you go over them too fast, they will move some though. I have pulled them up when larger vehicles coming (septic truck, pole truck). I plan to move them this summer to run a water hose through to a flower bed. I may update my review after that to see if the flaps will stay shut with a garden hose running through them.