Superior Threads So Fine 3-Ply 50 Weight Polyester Sewing Thread Spool - 550 Yards (#431 Navy)THREAD SPOOL: Features one 550 yard spool of Superior Threads So Fine! 50-weight thread made from 3 plies of 100% polyester100% POLYESTER: So Fine! is an extra smooth all-purpose polyester threadLINT FREE: Due to its' fine lint-free nature and matte-finish, this thread is an excellent blending thread for all types of projectsPERFECT FOR CRAFTING: So Fine! threads are excellent for sewing, serging, quilting and for your bobbinsMACHINE USAGE: Ideal for all types of quilting and sewing machines