We supply 2 sizes of tube or hosepipe:  (a) 1/2" (13mm) Black Polytube which is compatible with hosepipes of 12 to 13mm diameter.  (b) 5mm diameter black Polytube which is used with our Drippers and Microsprays.  These are high quality, Irrigation specification, flexible tubing.  They are compatible with our range of fittings, and most other makes too.  We have a complete range of connectors and fittings for above-ground installation and also hidden  sub-soil systems (hidden, apart from sprayheads and riser tubes).