Quick-Change Couplers, Part B and Adapters, Part F with easy-grip Compression Nut require no welding or epoxy to assemble your pneumatic conveying systems. All Couplers and Adapters with Compression Nuts are made of aluminum. They are designed for low pressure conveying systems and field installation, for use with .065 tubing size from 1 1/2 inches to 3 inches.