Flexible couplings are designed to correct small misalignments between close spaces. A flexible coupling has a thinner wall, compared to a flexible hose. A flexible hose is designed to span large spaces, or where a short flexible coupling will not work. Braided metal coverings can be ordered on hoses to protect the bellows. Our edge-welded bellow couplings and hoses can be compressed, bent or expanded to fit the application. PVC hoses with embedded spiral wire are available as a low-cost, flexible rough vacuum line, but they have higher permeation than metal bellows hoses, and PVC hoses cannot be compressed or extended.