Automotive fittings establish and maintain sealed connections within fluid and gas systems. Commonly used throughout engine, fuel, brake, and HVAC systems, they join lines, hoses, and components to prevent leaks under pressure and temperature variation. Materials include brass, stainless steel, aluminum, and plastic, selected for fluid compatibility and strength requirements. Connection types encompass compression, flare, o-ring, quick-connect, and threaded designs, each utilizing specific sealing mechanisms. Precise thread standards (NPT, BSP, SAE) and dimensional accuracy are critical for proper function and system integrity. Fittings are specified by port size, thread type, material, and connection style.