<HTML>Dan and list: Until recently I thought that the SF10 had accu-just hitch pins and the susp= ended plate system, while the F had the traditional hitchpin arrangement.&nb= sp; However, in the past year I have seen an SF which had the older style hi= tchpin setup.  The serial number dated it to 1969.  Apparently, th= ere was a time when the SF scale was still made with the old plate system.&n= bsp; For some reason I see quite a few SF's around town, but few F's. &= nbsp;  My kids' piano teacher has an F, but that's the only one that co= mes to mind.  I think that it does have tunable duplexes.  Yes, it= is a nice piano.  Roy Peters Cincinnati</HTML>