Universal Compatibility Compatible with most 3" x 5" gas tankless water heaters, including brands like Rinnai, Navien, Rheem, and A.O. Smith. Offers a safe and reliable venting solution for various setups. Venting Kit Includes : one 3" x 5" straight pipe, length of 21 inches, it ensures quick and hassle-free setup. Durable 304 Stainless Steel Constructed from high-quality 304 stainless steel for superior corrosion resistance, high-temperature tolerance, and UV protection. Built to last in demanding conditions. Efficient Indoor Air Quality Control Safely directs high-temperature exhaust gases outdoors, helping to maintain indoor air quality. Space-Saving & Flexible Design Compact, ideal for both residential and commercial installations where space optimization is essential. 3"x5" Vent Kit, Compatible with Navien Rinnai Rhemm A.O. Smith 21" Stainless Steel Pipe for Tankless Water Heaters, 304 Stainless Steel