The YJR is a direct plug-in replacement adapter for use in most amplifiers that use 5AR4/GZ34, 5U4, 5Y3 or similar full-wave rectifier tubes. The YJR converts your amp's vacuum tube rectifier to a solid state rectifier, reducing tube sag for a tighter sound and feel. The tube rectifier can easily be swapped back in when sag is desired. This Yellow Jacket® is a solid state device and as such does not require vacuum tubes.