The cars can effectively isolate sandstone, keep the water clean,
Two barrels of water washing method is the best tool to make sand class dirt sink won't float up.

In the simplest and the most bottom to avoid the cost of your valuable paint surface scratches.
When cleaning your vehicle, separating the gravel on the gloves.
Sand cars to prevent your paint, improper washing swirl marks.
Every time you go back to the bucket of water, sand and gravel cars will extract the surface of the radial design your car washing gloves particles, such as dust, sand and dirt from providing a clean, no scratch car washing gloves,
Once dirt settling at the bottom of the barrel, sand cars will remain separated into four quadrants of the washing water, so water won't interference.
Sand cars is ?