It's Sew Emma - 2.5" Half Square Triangle Paper Triangles on a Roll #H250
Foundation Paper Piecing -
Makes 700, 2.5" finished half square triangle blocks. Triangles on a Roll triangle paper allows you to create perfectly accurate half-square triangle units in any size and amount you need for your next quilt. Unroll and cut just what you need, then roll it back up for easy storage. Directions call for fabrics to be cut 7.5 wide.