AHDM04-18-21PN is a Shell Size 18 receptacle connector from Amphenol Sine Systems' DuraMate™ AHDM series, designed as a heavy-duty, environmentally-sealed circular connector for harsh-environment applications. The connector features a pin configuration with 21 contact positions and is constructed from metal (aluminum or zinc alloy) with integrated wide threading for secure bayonet or blind mate coupling. Operating at 250V, this receptacle is engineered to meet industrial standards including ISO 11783 for agricultural ISOBUS applications, providing reliable performance in off-road and demanding field environments. The connector's sealed design and robust construction make it suitable for tractors, implements, and other agricultural or industrial equipment requiring durable, weather-resistant interconnections.