King Tut is a thread produced by Superior Threads. It is a 40 weight, cotton thread that comes in varigated colors. This thread will have a higher contrast when used when on your quilt top.
So Fine! is a thread produced by Superior Threads. It is a 50 weight, polyester thread that comes in solid colors. This thread will blend in with your quilt more, and you will see less of this thread on your quilt top.