The Security Chimneys Secure Stack® CIX and CAX venting systems are designed to offer the ultimate in installation convenience and versatility for a variety of applications. Certified for commercial chimney, grease duct (CIX only) and diesel exhaust applications. Thick-gauge material for the inner pipe and coupling provides a strong and rigid assembly. Self-centering flue design significantly simplifies and accelerates the installation process. Coupling configuration (patent pending) requires only one locking band and the use of a regular, less expensive, high-temperature silicone sealant. Available in sizes from 5″ to 36″ diameters.