Micro Couplers are used to join two segments of MicroDucts. Straight and Transition couplers are available. (Manufacturer material and distributor product pages identify part 20001518 as the 18mm Straight Coupler 18/14mm (OD/ID). Provides an air- and water-tight connection; color-coded by size; tested to CENELEC EN 50411-2-8; approved to 232 PSI / 16 Bar.)