The diagnostic quick coupling plug with integrated shut-off valve and external NPT thread is a reliable solution for precise pressure measurement in hydraulic power systems. Manufactured in compliance with ISO 15171-1 and SAE J1502 standards, it guarantees full interchangeability with couplings from other leading brands. Designed from hardened, galvanized steel and sealed with durable NBR, it ensures long-lasting performance even under demanding conditions, with an operating temperature range from -40°C to +120°C. The plug withstands a working pressure of 400 bar and a burst pressure of up to 1600 bar when disconnected, while in connection with the socket it maintains 400 bar working pressure and 1300 bar burst pressure. Both plug and socket are equipped with valves that provide secure, leak-free operation, minimizing oil loss to just 0.1 ml during disconnection and limiting air inclusion to 0.02 ml during connection. Their flat sealing surfaces further enhance system cleanliness and efficiency, making them ideal for applications where precision and reliability are critical. With a vacuum resistance up to 0.9 bar and a hydraulic oil flow rate of 4.2 l/min at Δp = 3 bar, this coupling plug offers outstanding performance and safety, ensuring smooth integration into modern hydraulic systems.