I thought it wouldn't matter, but tried them anyway -- what a difference -- with my Sapphire which likes to "eat the first stitch" -- not even an appetite any longer! Haven't used them enough to say how long they will last, but am extremely pleased not having to be so careful about loosing the fabric under the stitch plate. Glad to hear the Klasse needles have a good top-stitch as they are less expensive then the Superior ones....