Plugs and caps are essential components within hydraulic systems, primarily used with tube connectors to prevent contamination and safeguard exposed ports. These fittings provide crucial protection against dirt, moisture, and debris entering the system during storage, transport, or maintenance. By securely sealing open ends, plugs and caps help to maintain the integrity and cleanliness of hydraulic circuits, ensuring optimal performance and extending the lifespan of valuable equipment. They are vital for system preservation.