Mylar 1" Right Triangle- 51 Piece Set - Quilting / Sewing Templates - Made in the USA! 50- 14 mil thick Mylar Templates. 1 -1/8" Thick 1 inch Right Triangle Acrylic Template Markings are laser engraved for long lasting use. Each Mylar piece is conveniently engraved with it's size for easy identification. Mylar pieces are sized to fit inside the acrylic template. Just cut your material around the Acrylic template and you are ready to sew around the Mylar. Mylar is heat resistant, use a household iron on low. Remove the Mylar with the hole after sewing. Use over and over! This Acrylic does have the 1/4" seam allowance and Guideline Holes. Right Triangle Size is 1" along left side and bottom of seam allowance lines. Matches up with our 1" Squares This acrylic part of the set is 1/8" thick acrylic. Mylar is a trademark of Dupont quilting tools, quilting supplies