Patio Products, Inc. stocks Sling Spline in three sizes, .180", .22" and .25".  Spline is sold by the roll and by the foot.  Sling Spline is available in clear only.  The size sling used will depend on the manufacture's frame size or the thickness of the fabric being used for the sling.  For replacement purposes, you should measure the thickness of the original sling spline.  Spline is designed to fit into the seam of sling fabric.  It is then slid into a sling rail on a chair frame.  Our vinyl, extruded for outdoor use, is commercial quality 100% virgin vinyl with ultra violet inhibitors manufactured into the product.