3-1/8 IN Internal Diameter: This 4-1/2 IN long coupling is designed to connect to a tube with a 3-1/8 IN diameter. It's commonly used on aFe POWER cold air intake systems, but can be used for a variety of projects.Flexible Bellows Silicone: Its bellows design is extremely flexible, making it easy to install, even when dealing with misaligned tubes. It allows for ample expansion, movement and vibration in-between two hard pipes. The built-in port holes (5/8 IN ID x 1 IN H and 3/16 IN ID x 1/2 IN H) allow for easy connection to PCV lines.Stainless Steel Clamps: Two corrosion-resistant stainless-steel worm clamps (#052) are included, providing a secure seal for virtually any application.Fitment Note: Not for use on pressurized side of supercharged or turbocharged applications.Direct Replacement for P/N 05-01404.