These are wheel cribs that are used to get your car off the ground. They come in many different sizes and variants. I got the 10" step wheel cribs. It comes in 2 pieces per wheel. The first step is about 5" tall and you first jack the car up and put the first steps on all four corners, then if you want you can use the additional interlocking piece to go up another 5" on all four corners. It is a safe way to lift your car and makes it much nicer to get underneath your car to work on. They are made of high density foam with a rhino liner type exterior that makes these things super strong but extremely light weight and resistant to your garage/car chemicals and fluids. Also if you need to store your car for some time these will prevent flat spots on your tires.
As far as price goes. They are not cheap. They are very proud of their product. My complete set for all 4 tires was $250 shipped. The ramps they make are also very pricey. But they are made in the USA and should last a lifetime.
I highly recommend these and i suggest you get the 2 piece step wheel cribs so it is easier and less stressful to lift your car.
Here is there website
http://www.raceramps.com but you can get em a tad cheaper on ebay.
also they make a ramp that extends off a trailer or lift ramp that makes it worlds easier to get on and off a trailer or ramp.
Here is my car sitting off the ground with plenty of clearance for me to work underneath.
