Mylar 4" Diamonds 51 Piece Set - Quilting / Sewing Templates 50- 14 mil thick 4" Diamond Mylar Templates. 1 -1/8" Thick 4 inch Diamond Acrylic Template Each mylar piece is conveniently engraved with it's size for easy identification. Mylar pieces are sized to fit inside the acrylic template. Can be ironed with low setting. Each side measures 2 3/8" along the seam line. This Acrylic does have the seam allowance and Guideline Holes. Diamond Size is Top to Bottom seam allowance lines 4". Top to Bottom overall size is 5". Just cut your material around the Acrylic template and you are ready to sew around the Mylar. -Mylar is a trademark of Dupont