High quality and reliable. My preferred compression fitting. Not cheap but quality never is. With a dedicated open ring spanner much easier to tighten where access is limited than fittings with hex or Octagonal nuts. Tool Station stock a double ended spanner for 15mm and 22mm fittings. My top tip is cut one in half with an angle grinder to give two stubby spanners which are easy to manipulate but still with more than sufficient leverage.