As others have stated, you don't have to have the same thread in both top and bottom. Sometimes I try to match the top thread, other times they are drastically different in color, weight, even type. This is especially true when I use specialty threads like metallic, holographic, monofiliment or super fine thread like Invisifil or silk. For these threads I always turn to Magnaglide Classic prewound bobbins which are different than the magnaglide delights (the delights are loaded with glide thread 40wt, the magnaglide classic doesn't specify but if I were to guess it is a 60 wt poly). No matter what I use, my Innova stitches beautifully as long as I take the time to make the proper tension adjustments.