High density bags are made of HDPE aka High Density Polyethylene. This strong but lightweight film is very economical to produce and to ship. At just 6 microns thick, these garbage bags are the lightest we sell, and are popular used as small wastepaper basket liners in bathrooms and offices. They are perfect for waste like tissues, office paper, and other lightweight trash. This category contains mainly small garbage bags between 3 and 10 gallon capacity.