^they fit looser pre-soak that the f310/3001 pre-soak, but post soak they are supposed to be almost identical. i heard that the sexfh shrinks WAY more than the f310 after a really hot soak. as much as almost 3 inches in the waist and elsewhere. they would have been fine if you kept them and soaked them assuming you got the same size as your f310's. i think you may have made a mistake in selling.