Our 68mm downpipe is available in 3 different lengths in most colours, these are 2.5m, 4m and 5.5m. Circular downpipe is usually used in conjunction with half round, deepflow and ogee gutter systems but it can also be connected to square gutters using the RDS2 adaptor.2.5m lengths are usually sufficient for rainwater pipe drops on single storey buildings, 4m and 5.5m lengths are generally used for buildings of two storeys and above. The pipe has an outside diameter of 68mm. Rainwater pipes are always a pushfit joint - never use silicon or solvent weld on these systems as there might be a requirement to take them apart for cleaning or unblocking at some point in the future.