Poly Tubing Poly Tubing may be installed above or below ground. Poly Tubing comes in five sizes: 1", 3/4", 1/2", 1/4", and 1/8". The 1" and 3/4" poly tubing are most often used as mainlines and lateral lines for both drip systems and traditional sprinkler systems made up of spray heads and/or rotor sprinklers. The 1/2" poly tubing is most often used as the main lateral or mainline into which drippers, micro sprinklers, or 1/4" barb fittings to connect the 1/4" micro tubing are inserted. Swing Pipe (funny pipe) is ideal for installing sprayheads in difficult and hard-to-reach areas and also works well for relocating existing sprinklers.