This rigid joiner is made from strong polypropylene. It's useful to make solid, rigid joints with push-in fittings that are dead straight. This is a good option to keep your connections plumb and true. The 50mm (2") length is long enough so even after pushing right into two Duotight 8mm fittings on both ends, you should still have an exposed length of about 3mm so you can still easily take the fittings apart later.
About Duotight Fittings - Duotight fittings are very high-quality, high-performance push-in fittings that use a double EPDM seal to ensure a solid, leak-free connection under a variety of situations. This makes it very easy to swap fittings and lines without clamps or fear of leaks.
To ensure a leak-proof seal, please cut tubing as squarely as possible, using a razor or very sharp knife. We recommend the Tube Cutter w/ Duotight Removal Tool for this.