I’ve recently knit a cardigan using Fivel and have just bought another sweater’s worth of it. I found that it knit up beautifully, with plenty of stitch definition. Ravelry calls it a worsted weight, but it’s got 100 meters or 220 yards/50 grams, which I’d called a heavy DK, similar in weight to a Cascade 220—although frankly Fivel is much nicer.