Synthetic clay mitts for car washing generally come in a few main types, which vary based on their intended use and abrasiveness:

1. Fine Grade: Used for light to moderate contamination removal without causing much abrasion to the paint surface.

2. Medium Grade: Suitable for moderate contamination removal, including tar, sap, and industrial fallout, while still being gentle on the paint.

3. Heavy Grade: Designed for heavy contamination removal, such as stubborn tar spots or heavily embedded dirt. This type may be more aggressive and should be used carefully to avoid marring the paint.

These grades may also be indicated by different colors or labeling by manufacturers. It's essential to choose the right grade based on the level of contamination on your car's paint surface to achieve effective cleaning without damaging the paint. Always follow the manufacturer's instructions for proper use and maintenance of synthetic clay mitts.