Wonder Clips have a wide opening for holding multiple layers of fabric. They won’t damage or distort your fabric, and you won't have to worry about accidentally sewing over pins! The. Wonder Clip base is flat for easy feeding to presser foot with 1/4″ and 1/2″ seam allowance markings on the base. Assorted colors - choose your favorite, coordinate your clips with fabric, or pick the one most easily seen!