Hmmmm....you and the vendor could both be right. My 1993 888 has exactly the same filler cap as my 2001 ST and all the 748's, 916's, Monsters and belt drive SS's I've ever seen, so they should be a direct fit.
However, if it's a quick release filler cap like the one you see on this 900ss, the buyers description might be right but it won't fit your bike
