This is a PCB from tubes 4 hifi used in their M-125 Monoblock amps. it is version 19. Diagram is included. I replaced the 47uf 400vdc with 47uf 450vdc for a little more protection. Also, the input triode vacuum tube is wired in parallel. Does not include tubes. If you don't want It worked in my project amp but is being sold as is. Please don't buy if you don't know what you are doing. I accept Paypal and ship USA only. Please view my other items.