These clipart images can be used on products for resale.
39 .png files (300 dpi resolution),
35 .jpeg files (300 dpi resolution).
The PNG format holds a transparency and does not have a white box around it. So you can drag and drop your backgrounds behind the template. Saving this format over and over doesn't degrade its quality at all. Please check if your graphic program supports this format.
The JPG format is more standard and widely accepted. Graphics are surrounded with white background and not transparent. Over time jpg images tend to loose their clarity and sharpness.