I'm not really sure. Mine is actually the Slice Premium "Plus" (note the little red + sign), which is lighter than the Premium. FYI, Premium is 440 grams uncut and the Premium + is 344 grams uncut. I don't know anything about the Slice "Ultra" forks. The Slice Si is the one that everybody wants because they were made by Time and they are the lightest. Somewhere in the 320-340 gram range I believe.