The 4FJ-3MJ Straight Reducer & Expander from Fittings Unlimited Inc is a versatile fitting designed to transition between different pipe sizes. This fitting features a 4mm female JIC connection and a 3mm male JIC connection, allowing for seamless integration into existing systems. Made from high-quality materials, it is built to withstand high pressures and is suitable for hydraulic applications. Its compact design ensures easy installation, while the durable construction guarantees long-lasting performance. This reducer and expander is ideal for professionals looking to optimize their fluid transfer systems.