Double branches in a soil stack have a number of uses, but essentially they are used for the purpose of connecting together multiple pipe runs, usually in a vertical plane. They are most commonly seen on external elevations, bringing a number of rainwater or above ground drainage runs together into a single soil stack. Three different angles are available in the 100mm option, these being 45, 69 and 88 degrees. In the 150mm size option they are only available with 45 degree branch entries. As Halifax pipes and fittings have no sockets, couplers are required to connect this branch to a pipe. A full dimensional drawing of this product can be found in the  Halifax technical catalogue.