A no-hub coupling joins two hub-less connections. No-hub couplings are commonly used to connect a grease trap to a no-hub cast iron pipe. They can also be used for soil waste, vent lines, and storm drainage applications. No-hub couplings have a shear-resistant metal sleeve, making for extremely durable fittings that can withstand waste and water flow for many years.
Mission couplings are used to connect a section of pipe into an existing run of waste line or vent.