It’s designed especially for cutting mat from the rear, or non-presentation side of the mat. Use this cutting head option when a delicate surface mat may be damaged by one of the front surface bevel cutting heads, or when cutting very thick or dense mats up to 4.4 mm in thickness. The 45° rear surface head can also be used to cut foam board with a bevel, which can facilitate the creation of thick mat spacers or foam board deep-bevel fabric wraps.