This is our favorite thread to sew with! Designed with award-winning quilter John Flynn, So Fine! #50 is a lint-free, low/medium sheen, smooth #50/3 filament polyester thread. Due to its fine nature, So Fine! #50 is an excellent blending thread commonly used for topstitching applications when the fabric or backing design is to be more prominent than the quilting. So Fine! #50 also makes a wonderful bobbin thread! Reduce the time spent cleaning your machine by using a quality thread like So Fine! #50.