Specially designed to fit your longarm bobbins. 12 Mega-size Magic Bobbin Teflon Washers, 7/8" diameter for "M" style bobbins which are larger than a conventional sewing machine bobbin. Great for longarm and midarm quilting machines that use style "M" bobbins. Long lasting Teflon is tough and durable. Eliminates backlash during high speed stitching.