Enhance your vintage audio equipment with this Mullard 5Z4G (CV1863) vacuum tube, made in the United Kingdom. This NOS (New Old Stock) tube has been tested with an AVO MKII and is ready to bring your sound system to life. The Mullard brand is renowned for its quality and durability, ensuring a long-lasting and reliable addition to your collection. This tube is perfect for enthusiasts who want to upgrade their vintage audio equipment to achieve the best possible sound.