Plasson Metric Reducing Coupling, 16mm to 110mm, PN16 This reducing coupling joins two different sizes of metric poly pipe. It covers a wide range of sizes, from 20mm down to 16mm right up to 110mm down to 63mm. Farmers and contractors use this fitting where pipe size steps down along a poly water line. It gives a secure, leak-free connection between the two different diameters. Features Available across sizes from 16mm to 110mm Rated to PN16 for reliable pressure handling Compression joint installs without special tools Corrosion resistant for long term outdoor use Instant seal on installation with a captive O-ring A solid choice for stepping down pipe size on metric poly water lines.