I think this might be a 115 - if my memory is correct, the Tiffany decals were only used on the 115's in the model 15 line.
I do tend to get details mixed up, though so don't take this as true until you can research it yourself.
If the hook makes a full rotation for each stitch, it's a 115 - if the hook rocks back and forth (oscillates) then it's a model 15 of some other sub-type.
The full-rotary operation of the hook makes the machine smoother, quieter and lessens the occasion of skipped stitches when free-motion quilting. Between this and the Tiffany decals, is it any wonder that this machine is on my wish list?
