These Royal Imports Green Floral Water Tubes are molded from unbreakable polypropylene plastic, while the caps are made from soft, rubber-like polyethylene. The middle opening in the cap stretches, allowing for a single-stem floral item to be placed through it, forming a water-tight seal to keep this water vial from leaking. Caps are included with tubes! Pik tubes can be placed into soil or floral foam to create arrangements for use in your home, garden or as a gift!