Home > Threads > Seracor Thread Formerly known as Metrocor. Seracor is a 100% Polyester Corespun Serger and Long Arm Quilting Thread. Can also be used for General Quilting and Sewing. Optimal elongation, exceptionally smooth and shrink proof. 2500m/2734 yds per cone. Available in 50 colors. Recommended needle size 70-80. Matte finish. Tex 24. Strength 120. 2-ply. 50 weight.