Lifetime guarantee! Make your business name stand out by mounting flat cut acrylic sign letters on your building or lobby wall. Acrylic sign letters are available in four thicknesses up to 1/2 inch and 30 colors that are pigmented solid through and through. Each individually cut acrylic sign letter comes complete with mounting hardware and installs in minutes. The acrylic is a high density polyethylene, HDPE, which offers better rigidity and tensile strength.