Hose conversion adapter: 3.9 inches (100 mm) φ to 2.2 inches (57.15 mm) φ 3.9 inches (100 mm) hoses and 2.5 inches (63.5 mm) φ hoses can be connected to a 3.9 inches (63.5 mm). The mouth of this adapter is 2.25 inches (57.15 mm) diameter, making it perfect for the dust collecting port of 2.5 inches (63.5 mm). Easy to connect with 2.5 inches (63.5 mm) diameter. By using the following adapters, it can also convert 3.9 inches (100 mm) φ to a usable 1.5 inches (38 mm) diameter with a vacuum cleaner.