Set up to replace a 5U4GB, 5Z3P, 5Z3PAT, 5Z3P-J or 5C3S rectifier valve, this single Tube Amp Doctor 5U4G-SV Premium Selected Rectifier Tube has a 5Y3-style design but with a higher output voltage, making it ideal for modern, American-made recto-style valve amplifiers in need of a little more headroom. This tube has been made in Germany according to strict quality-controlled standards.