Free sander fits the hand like glove, it's human-engineered to be less tiring over longer periods of operation for big jobs, and compact enough to permit working easily in corners and other tight spots.
#180 paper for trimming and surface polishing nonferrous metal such as aluminum,zine die casting,etc
#240 paper for fine finishing and polishing quality wooden products furniture, frames and other items.
#280 paper for surface polishing stone, lacquer, putty, metal
#360 paper for polishing polyester, putty and similar materials