57 four input 5F6 Fender Bassman. This is the one with the unusual mercury vapor rectifier tube. Rectifier tubes last a long time and if you need another they are readily available online contrary to conventional wisdom. Tone wise, the 5F6 is pretty much the same as the highly regarded 5F6-A; the big difference being the rectifier tube. This one has all original tweed and grill cloth as well as original transformers and speakers. Speakers are all from 1957 and are original to this amp. Most of the caps have been replaced with orange drops making the amp reliable for the next 40 years or so. It's nice to get a Fender tweed with original caps but if you plan on gigging and recording, you would probably end up replacing the caps anyway to make it reliable and quiet enough. This amp is loud and the breakup comes on smoothly but it's going to come on at a louder volume than you might want in your living room. This is a great sounding amp that I wouldn't hesitate to take on the road. There is one issue-someone added a bushing to the bottom, presumably to be able to mount the amp on a stand. Useful, I suppose but not recommended.