Coats Ultra Polyester Bobbins #M Size 138 Black (144 pack) offers pre-wound, continuous filament polyester thread designed for durable and precise stitching. With high tenacity and a bonded, heat-set finish, these bobbins resist stretch and shrinkage while providing strength comparable to nylon. The black Size 138 (Tex 135) M style bobbins are UV resistant and suitable for use with fabric, leather, canvas, and vinyl in commercial sewing machines. Ideal for upholstery, marine fabric, furniture, and seat trims, these bobbins deliver noticeable stitches and lasting performance in outdoor and heavy-duty applications.