The Fons and Porter refills are a lot cheaper than the Sew Line and as far as I know are the same thing. Where I buy mine locally, you get 6 pieces of the Sew Line or 10 of the Fons and Porter. They are the same price, so I buy Fons and Porter. I have been using the white to mark my dark background for applique of the Affairs of the Heart blocks which Candi mentioned previously.