Flintlastic® STA Plus is a premium, APP-modified bitumen, versatile, smooth-surface membrane. It is designed for use as a robust base, interply or cap membrane over various types of substrates for both new construction and reroofing installations. Flintlastic STA Plus is produced with a high-performance, stress-resistant polyester matt which is impregnated and coated with a superior grade, APP-modified bitumen compound.