The basis of our tube system consists of 1.8mm semi-rigid plastic tubes. These tubes are designed to be used inside our 3mm tubes or as a liner inside our copper tubes. Although many tiers do tie on these tubes directly, they are not intended for that, and may fail over time. A much better approach is to use the 1.8mm tube as a liner and let it stick out of front of the 3mm tube so a small head can be created. For more info on this please see our videos and articles on this. The tubes are sold in 10-packs with tube lengths of 20 cm (8″).