The tubing should have a large flow-through opening, and minimize the chance of clogging. Therefore, the pipe thickness must be the same as the stop edge in the fittings so that there is a seamless connection inside. A requirement for this is that you shorten pipe at right angles. You can therefore install a central vacuum system using standard pipe, but the chance of clogging is slightly higher. The best result is obtained by using original Better Tube with corresponding original long bends and tees.