I bought 2 of these, one to keep in my truck for road side emergencies and the other for automotive work use at home. The few times I have used them they work well, but just so you know they have a recommended expiration date on them. I think this is due to their intended use as a RV chock, where they would sit in the sun a lot and would degrade. But again they are cheap, and if the worries you, just buy a new one and toss out the suspect one!