Our 87mm steel downpipes are used with the 100mm and 135mm gutter systems and the 100mm downpipe connects to the 150mm gutter system.Downpipes should be connected to the outlets using a pipe connector. Pipes should be clipped at spacings of 1.8m maximum.87mm downpipee can be connected to 110mm drainage using a D96 adaptor. Insert the adaptor onto the steel downpipe prior to inserting it into the drainage pipe or fitting. In the case of 100mm downpipes (for the 150mm gutter system) these can be connected directly into a 110 mm ring seal connection.