M Kelsey noted: >>Whoops, actually, they're oil-filled. >>http://www.accutronicsreverb.com/history.htm Ah! Pretty neat stuff! (Dang phone company pops up everywhere!) >>So, it has TWO seperate springs. It sounds *great* when you pick up >>an inch and drop it on the floor. Heh. I know that sound!! My first amp was similar to this: http://www.home-wrecker.com/rocket2.html On the floor of the case was a metal (aluminium?) rectangle about 4" by 15" or so housing the reverb springs. So yeah - I know that 'drop' sound! ;-) RonL.