The ball bearing swivel action allows for easy alignment of couplings and permits hose assemblies to be easily handled. They can also prevent hose failure from excessive twisting or kinking. They are available in sizes 1-1/2" to 6" in aluminum and stainless steel (bearings are stainless with a Viton seal). Swivel repair kits are available (D40LS-xxxVI). Always confirm if gasket material is compatible with fluid.