This tube/valve is used but tested 100%. The manufacturing code is F32 B4K3 which indicate Blackburn manufacturing. This vintage Mullard GZ34 full wave rectifier is a quality product from the United Kingdom. Its brand is well-known for producing reliable and durable electronics. This unit quantity of one is perfect for those who are looking to add a touch of vintage to their audio and video setup. The GZ34 is a great addition to any collection of vintage tubes and tube sockets, as well as vintage parts and accessories. It is a versatile piece of vintage electronics that is sure to enhance the sound quality of any consumer electronics. The Mullard GZ34 is an excellent choice for those who appreciate the quality and craftsmanship of vintage electronics. Shipping is by DHL and is usually delivered within 5-7 days.