Used for water supply networks with a nominal pressure of 10 bar (calculated for a temperature of 20°C), installed buried in the ground. Manufacturing method by mechanical processing on machines for electrofusion couplers made of PE100, with the electrofusion fitting resistance embedded in the material with dimensions corresponding to SDR 17 (ISO S8), according to EN 12201-3:2011+A1:2012 and EN 1555-3:2010+A1:2012. The active restraint system is ensured by pipe-in-pipe manufacturing technology. In this way, no auxiliary devices are required for installation. Welding voltage 40 V. 4 mm connectors. Welding is performed by authorized welders with appropriate equipment and in compliance with the welding procedure. Welding is carried out in two separate welding zones, which are also welded in a single welding sequence without preheating, one for one end and one for the other end of the coupler.