The light blue cloth I bought at BJ's. It is 80% polyester and has an excellent what I call "drag" or grabbing when used wet. You can also find these at Walmart in the car section, though not as cheap. Walmart is about 5 for $5.00, BJ's is 25 for a pack of 25, (last time I checked).
The dark blue cloth is 100% polyester that I found at a dollar store. It is only useful for dusting, no "grab" at all!!
Do not you dryer sheets, softener, or bleach on any of these.