This type saw is used to cut out forms from sheets, to shorten bars
or tubes or to give whatever the needed size.
The saw blade in the picture is the small line between the bottom two screws. There are different sizes for this blades from aprox. 0.2 mm to 1 mm thickness. Common used size is 0.2 - 0.4 mm , depending on given facts.
The thicker the blade, the more material is lost at cutting, but the cut is straighter, especially in thick materials. Contrary a thinner blade destroy less material but tends to give a uneven cut.