This has the factory metal mod which makes the amp tighter with tons more gain and aggression. This has dual masters, depth and nfb on the back and it even has switches in the back to change channels and engage boost the footswitch is not necessary like on other mezzabarbas but the footswitch is still included. This is like New and has a new set of 7581 a tubes which are a higher headroom more dynamic 6l6. All and all this is one of the most impressive amps you can play/own. selling because I have two of these. 3600 shippeed pp ff